DE112010003961B4 - Photoelectric conversion element, light receiving device, light receiving system and distance measuring device - Google Patents

Abstract

A photoelectric conversion element for detecting light and converting the light into photoelectrons, comprising:
a first MOS diode (18a) having a first electrode (16a) formed on a semiconductor substrate (12) with an insulator (14) therebetween; and
a plurality of second MOS diodes (18b) each having a second electrode (16b) formed on the semiconductor substrate (12) with the insulator (14) therebetween;
wherein the first electrode (16a) of the first MOS diode (18a) has a comb-like shape as seen from an upper side thereof in which a plurality of branch portions (22) are branched from an electrode portion (20), and
all of the second electrodes (16b) are separated from the second MOS diodes (18b) from the first electrode (16a) and are each interposed between the plurality of branch portions (22) from the first electrode (16a), as viewed from the top thereof; are embedded,
wherein a potential under the first electrode (16a) from the first MOS diode (18a), and potentials among the second electrodes (16b) from the second MOS diodes (18b) are respectively and independently controlled,
that at least the photoelectrons generated by photoelectric conversion at the second MOS diodes (18b) migrate to the first MOS diode (18a), and
wherein within the first MOS diode (18a), a portion corresponding to a base (24) of the one electrode portion (20) of the first electrode (16a) is formed as a charge collecting unit (26).

Description

Technical area

The present invention relates to a photoelectric conversion element which converts light into an electric charge according to the amount of light thereof, a light receiving device which obtains luminance information of incident light to the photoelectric conversion element in a predetermined period of time, a light receiving system in which the influence of ambient light is detected using the light source A photoelectric conversion element is controlled, and a distance measuring device in which the principles of a transit time (TOF) method using the light receiving system are applied.

Technical background

Heretofore, there has been proposed an image sensor capable of signal acquisition in a high S / N ratio while removing the influence of ambient light (see Koji Yamamoto, "Furiwake Tenso Hoshiki Oyobi Bubun Ryoiki Kosoku Yomidashi Hoshiki ni yoru Hencho Hikari Seibun Kenshutsu Kano na CMOS Image Sensor ni Kansuru Kenkyu (Research in relation to CMOS Image Sensors Capable of Modulated Light Component Detection by Allocated Transfer and Subregion High Speed Readout Methods ) , Graduate School of Materials Science, Nara Institute of Science and Technology, March 2006, hereinafter referred to as Document 1). The image sensor disclosed in the document 1 detects modulated light components using a charge allocation transfer method. However, the pixel circuit thereof has a structure in which two ordinary PG (Photogate) process image sensors are used in combination and assembled with a conventional PG as a light receiving element. Such an image sensor includes a structure in which there are two transfer gates sandwiching a light receiving element and signal charge accumulating units are disposed on respective outer sides of the transfer gates. Further, according to the document 1, in order to increase a sensitivity, a structure is proposed in which the PG content formed by polysilicon is reduced. In particular, an example is disclosed in which the PG is formed in a comb-like shape.

Further, as an example application of an image sensor, a distance measuring system is known for measuring the distance to an object in a non-contact manner. Such a distance measuring system uses a time of flight (TOF) method. The TOF method works by radiating light with respect to an object, measuring a period of time from radiating the light to striking the light on an object and bouncing and returning the light, and then the distance to the object based thereon Period and the speed of light measured (see Ryohei Miyagawa and Takeo Kanade, "CCD-Based Range-Finding Sensor," IEEE Transactions on Electron Devices, Vol. 44, No. 10, October 1997, pages 1648-1652 , below as a document 2 designated).

According to the document 2 In detail, the irradiation timing of pulsed light in a distance measuring system and the operation timing of two light receiving elements are disclosed. Specifically, irradiation timing and irradiation stop timing of pulsed light having the same length are repeated (that is, the light-emitting element is operated at a duty ratio of 50%), and charges are alternately bidirectionally in synchronization with emission and non-emission of the transmitted pulsed light (see 1 from document 2). In addition, a period over which the pulsed light is reflected by an object and returns is measured based on the phase difference of two output voltages.

US 2007/0158770 A1 discloses time-of-flight distance meter and discloses a photoelectric conversion element having two MOS diodes with electrodes on a semiconductor body with an insulator therebetween, both electrodes being comb-like in shape and branched with branches from a portion of the electrodes and both electrodes separated from each other and each embedded between branches of the other. Both electrodes are controlled in such a way that at least partially the photoelectrons also migrate from one electrode comb to the other. The shape of the branches is rectangular in each case.

Furthermore, the aims US 2007/0158770 A1 to produce a maximum-power range sensor at low cost by adding as few manufacturing processes as possible to a standard CMOS manufacturing process. Further, the US 2007/0158770 A1 a silicon substrate ( 20 ), on which an oxide layer ( 3 ) is trained. On the oxide layer are two photogate electrodes ( 1 . 2 ) provided for the charge exchange. At the ends of the oxide layer are floating diffusion layers ( 5 . 6 ) for removing charges from a photodetector layer ( 4 ), and on the outside thereof are a gate electrode for Reset and a diffusion layer for providing a reset voltage provided.

US 4 808 833 A discloses image sensors comprising a photoconductive film and opposed electrodes contacting the photoconductive film. The image sensors include a photoconductive layer assembly that is divided into multiple groups and a common electrode that connects each of the ends of the photoconductive layer assembly for each group. The image sensor consists of first wires, second wires and an insulating layer formed on an insulating substrate. The first wires are connected to the other ends of the photoconductive layer assembly. The second wires cross the first wires and connect, via the first wires, the ends of the groups that correspond to each other. The insulating layer insulates the first wires and the second wires from each other. In addition, the image sensors are formed by extending the photoconductive film into a region of the first and second wires. The extended section is the insulating layer.

Overview of the invention

Incidentally, in order to realize a distance measuring device by a TOF method, it is necessary that received photoelectrons (that is, charges obtained by photoelectric conversion) are transferred at high speeds.

In the image sensor of the above-mentioned document D1 for improving sensitivity, an example in which the PG (Photogate) is formed in a comb-like shape is disclosed. In this case, within the light receiving element, the PG portion thereof has a function to transfer stored charges (photoelectrons) to an output side. However, apart from the PG, portions thereof have no such function. Consequently, there arises a problem that time is necessary to transfer all the photoelectrons stored in the light receiving element to the output side.

Further, in terms of receiving mixed light consisting of ambient light and modulated light with a certain timing, and receiving modulated light with different timing, it is necessary that charges alternately in two directions in synchronization with a broadcast and non-broadcast of the modulated light to be transferred. For this purpose, photoelectrons which are photoelectrically converted in the photoelectron conversion element must be transferred at high speeds to respective nodes via desired gate electrodes. In particular, in order to obtain a sufficient signal-to-noise ratio (S / N ratio), a photoelectric conversion element having a large light-receiving area is required. However, in the case where a large photoelectric conversion element is used, the distance to the output node becomes long, and hence it is difficult for the photoelectrically converted photoelectrons to be transferred at high speeds to a desired node.

Further, in the case where two photoelectrons are assigned to two nodes of the photoelectric conversion element, if the distances to respective gate electrodes from the photoelectric conversion element are different, then a difference in the transfer efficiency to the two nodes occurs, resulting in a reduction in S / N ratio, which is caused by the presence of an in-plane distribution in the conversion efficiency of the photoelectric conversion element or differences in the transmission paths from the photoelectrons.

The present invention has been made in view of the above-mentioned problems and has an object to provide a photoelectric conversion element in which photoelectrons obtained by photoelectric conversion can be transferred at high speeds to a desired region and collected or stored therein, in which Distance measuring device can be realized by applying the principles of a TOF method, and which further allows the invention to be applied to various light receiving devices.

Another object of the present invention is to provide a light receiving device in which luminance information of incident light can be obtained most accurately within a predetermined time period using the photoelectric conversion element having the above-mentioned effects, the light receiving device being further combined with an electronic shutter function ,

Another object of the present invention is to provide a light receiving system in which the S / N ratio can be improved, the influence of ambient light interference components can be reduced, and which enables necessary light components to be detected with high accuracy.

Yet another object of the present invention is a distance measuring device in which the S / N ratio can be improved, the influence of ambient light perturbation components can be reduced, and which enables the distance to an object to be measured with high accuracy.

[1] A photoelectric conversion element for detecting light and converting the light into photoelectrons according to a first aspect of the present invention includes a first MOS diode having a first electrode formed on a semiconductor substrate with an insulator therebetween, and a plurality of second MOS diodes each having a second electrode formed on the semiconductor substrate with the insulator therebetween, the first electrode of the first MOS diode having a comb-like shape as seen from an upper side thereof in which a plurality branched from branch portions of an electrode portion, and all of the second electrodes of the second MOS diodes are separated from the first electrode, and each embedded between the plurality of branch portions of the first electrode, as seen from the top thereof, wherein a potential under the first electrode of the first MOS Diode and potentials among the second electrodes are respectively and independently controlled by the second MOS diodes such that at least the photoelectrons generated by photoelectric conversion at the second MOS diodes migrate to the first MOS diode, and wherein within the first MOS diode, a portion corresponding to a base of the one electrode portion of the first electrode is formed as a charge collecting unit.

[2] In the first aspect of the present invention, the plurality of branch portions of the first electrode in the first MOS diode and the second electrodes of the second MOS diodes are each rectangular-shaped.

[3] In the first aspect of the present invention, all of the plurality of branch portions of the first electrode in the first MOS diode are formed to gradually increase in width toward the one electrode portion, as viewed from the upper side all of the second electrodes of the second MOS diodes are shaped so as to gradually narrow in width toward the one electrode portion, as seen from the top.

[4] In the first aspect of the present invention, first power supply terminals of each of the plurality of branch portions of the first electrode in the first MOS diode and second power supply terminals of each of the second electrodes in the second MOS diodes are formed at positions are maximally separated from the charge collecting unit, viewed from the top.

[5] A light receiving device which obtains luminance information of incident light according to a second aspect of the present invention comprises a photoelectric conversion element which detects the incident light and converts it into photoelectrons, a charge collecting unit for collecting photoelectrons derived from the photoelectric Conversion element, a capacitor storing the photoelectrons in a predetermined period of time, a charge-dispense unit emitting the photoelectrons, a first MOS-type switching element interposed between the charge collecting unit and the capacitor to cause in that the photoelectrons collected in the charge collection unit migrate to the capacitor, and a second MOS-type switching element disposed between the charge collection unit and the charge-discharge unit for discharging the photoelectrons from the charge collection unit to the charge collector cargo gave control unit. The photoelectric conversion element comprises a first MOS diode having a first electrode and a plurality of second MOS diodes having second electrodes, the first electrode of the first MOS diode having a comb-like shape as viewed from an upper side thereof in which a plurality of branch portions are branched from an electrode portion, all of the second electrodes of the second MOS diodes being separated from the first electrode and embedded between the plurality of branch portions of the first electrode, as viewed from the upper side, and the photoelectrons are transferred from the photoelectric conversion element to the capacitor by selectively controlling an opening / closing of the first switching element and the second switching element, luminance information of incident light based on an amount (charge amount) of the photoelectrons transferred to the capacitor be reached.

[6] In the second aspect of the present invention, the charge collecting unit is connected to the photoelectric conversion element, and the charge discharge unit is arranged to face the capacitor while the charge collecting unit is sandwiched therebetween.

[7] In the second aspect of the present invention, the capacitor comprises a MIM capacitor or a MOS capacitor or a capacitor embedded photodiode structure or parasitic pn junction capacitance.

[8] In the second aspect of the present invention, at least the charge collecting unit, the first switching element, the second switching element, and the capacitor are formed in a light-shielded area.

[9] A light receiving device which obtains luminance information of incident light according to a third aspect of the present invention comprises a photoelectric conversion element which detects the incident light and converts it into photoelectrons, a charge collecting unit for collecting photoelectrons generated by the photoelectric conversion element , a first capacitor and a second capacitor storing the photoelectrons at predetermined time periods, a charge-dispense unit discharging the photoelectrons, a first MOS-type switching element interposed between the charge collecting unit and the first condenser in the charge collecting unit, photoelectrons accumulated in the charge collecting unit selectively associate with the first capacitor, a second MOS type switching element disposed between the charge collecting unit and the second capacitor to charge the photoelectrons collected in the charge collecting unit tively assign the second capacitor, and a third MOS-type switching element to control a discharge of the photoelectrons from the charge collecting unit to the charge-dispense unit. The photoelectric conversion element comprises a first MOS diode having a first electrode and a plurality of second MOS diodes having second electrodes, the first electrode of the first MOS diode having a comb-like shape as viewed from an upper side thereof in which a plurality of branch portions are branched from an electrode portion, all of the second electrodes are separated from the second MOS diodes of the first electrode, and are respectively sandwiched between the plurality of branch portions of the first electrode, as viewed from the top, and the photoelectrons are transferred from the photoelectric conversion element to the first capacitor and the second capacitor by selectively controlling ON / OFF states of the first to third switching elements, wherein luminance information of incident light is based on an amount (charge amount) of the photoelectrons, which d em first capacitor and the second capacitor are obtained is obtained.

[10] In the third aspect of the present invention, the charge collecting unit is connected to the photoelectric conversion element, the charge discharge unit is disposed so as to face the photoelectric conversion element while the charge collecting unit is sandwiched therebetween, and the first capacitor and the second capacitor are arranged so as to oppose each other while the charge collecting unit is sandwiched therebetween.

[11] In the third aspect of the present invention, the first capacitor and the second capacitor include a MIM capacitor or a MOS capacitor or an embedded photodiode structure or a parasitic pn junction capacitance.

[12] In the third aspect of the present invention, at least the charge collecting unit, the first to third switching elements, the first capacitor and the second capacitor are formed in a light-shielded area.

[13] A light receiving system according to a fourth aspect of the present invention includes a light emitting device that emits pulsed light with respect to an object, a light receiving device that receives reflected light from the pulsed light and performs an output in response to a received light amount, and a controller - / Control device, which controls the light-emitting device and the light-receiving device / controls. The light receiving device comprises a photoelectric conversion element which detects and converts the reflected light into photoelectrons, a charge collecting unit for collecting photoelectrons generated by the photoelectric conversion element, a charge discharge unit for storing a pair of capacitors which store the photoelectrons at predetermined time periods, which outputs the photoelectrons, a pair of MOS type switching elements disposed between the charge collecting unit and the pair of capacitors to selectively supply the photoelectrons collected by the charge collecting unit to the pair of capacitors in synchronization with a drive of the light emitting device and a third MOS-type switching element for controlling a discharge from the photoelectrons from the charge collecting unit to the charge-dispense unit in synchronization with a drive of the light-emitting device. The photoelectric conversion element comprises a first MOS diode having a first electrode and a plurality of second MOS diodes having second electrodes, the first electrode of the first MOS diode having a comb-like shape as viewed from an upper side thereof in which a plurality of branch portions of an electrode portion are branched, wherein all of the second electrodes of the second MOS diodes are separated from the first electrode and each embedded between the plurality of branch portions of the first electrode, as seen from the top. The controller turns ON a first switching element of the pair of switching elements, and transfers the photoelectrons from the photoelectric conversion element to a first capacitor of the pair of capacitors, in a first period which is within a period in which the pulsed light is not radiated by the light-emitting device, turns ON a second switching element of the pair of switching elements, and transfers the photoelectrons from the photoelectric conversion element to a second capacitor of the pair of capacitors, in a second period which is within a period in which the pulsed light is emitted from the light-emitting device, the third switching element turns ON, and controls the charge-dispense unit to discharge the photoelectrons from the photoelectric conversion element within a period outside the first period and unconfirmed d of the second period, and obtains luminance information of the reflected light based on an amount (charge amount) of the photoelectrons transferred to the first capacitor and an amount (charge amount) of the photoelectrons transferred to the second capacitor.

[14] In the fourth aspect of the present invention, there are further provided a power source and a first reset switch of the MOS type and a second reset switch of the MOS type to set potentials of the first capacitor and the second capacitor to initial potentials.

[15] In the fourth aspect of the present invention, further, a first amplifier and a second amplifier are provided for respectively converting into electrical signals of a level corresponding to potentials based on the amount of photoelectrons stored in the first capacitor and the second capacitor.

[16] In the fourth aspect of the present invention, there are further provided a first charge holding unit and a second charge holding unit formed of a MOS capacitor or an embedded photodiode-structured parasitic capacitance to temporarily store the photoelectrons are transferred from the first switching element and the second switching element, and a first charge transfer unit and a second charge transfer unit are provided, which is formed by MOS-type switching elements to the photoelectrons, which temporarily in the first charge-holding unit and the second charge holding unit are stored to transfer to the first capacitor and the second capacitor.

[17] A light receiving system according to a fifth aspect of the present invention includes a light emitting device that emits pulsed light with respect to an object, a light receiving device that receives reflected light from the pulsed light and performs an output in response to a received light amount, and a controller - / Control device, which controls the light-emitting device and the light-receiving device / controls. The light receiving device comprises a photoelectric conversion element which detects and converts the reflected light into photoelectrons, a charge collecting unit for collecting photoelectrons generated by the photoelectric conversion element, first to fourth capacitors storing the photoelectrons at predetermined time periods, a charge discharge unit, which outputs the photoelectrons, first to fourth MOS-type switching elements arranged between the charge collecting unit and the first to fourth capacitors for assigning the photoelectrons to the first to fourth capacitors in synchronization with a pulsed light emission, and a fifth one MOS-type switching element disposed between the charge collecting unit and the charge-discharging unit for controlling supply of the photoelectrons from the charge collecting unit to the charge-discharging unit. The photoelectric conversion element comprises a first MOS diode having a first electrode and a plurality of second MOS diodes having second electrodes, the first electrode of the first MOS diode having a comb-like shape as viewed from an upper side thereof in which a plurality of branch portions are branched from an electrode portion, all of the second electrodes of the second MOS diodes being separated from the first electrode and embedded between the plurality of branch portions of the first electrode, respectively, as viewed from the top. The controller controls irradiation of the pulsed light by the light emitting device and ON / OFF switching of the first to fourth switching elements, turns ON the fifth switching element, and outputs the photoelectrons to the charge output unit at a time when all first to fourth switching elements are turned OFF, and obtains luminance information of the reflected light based on an amount (charge amount) of the photoelectrons transferred to the first to fourth switching elements.

[18] In the fifth aspect of the present invention, there is further provided a power source and first to fourth MOS-type reset switches for setting potentials of the first to fourth capacitors to initial potentials.

[19] Further, in the fifth aspect of the present invention, first to fourth amplifiers are provided for respectively converting to electrical signals of levels corresponding to potentials based on the amount of photoelectrons stored in the first to fourth capacitors.

[20] In the fifth aspect of the present invention, there are further provided first to fourth charge holding units constituted by a MOS capacitor or an embedded photodiode structured parasitic capacitance to temporarily supply the photoelectrons transferred through the first to fourth switching elements and first to fourth charge transfer units formed of MOS type switching elements for transferring the photoelectrons temporarily stored respectively in the first to fourth charge holding units to the first to fourth capacitors, respectively.

[21] In the fourth and fifth aspects of the present invention, a structural member of the light receiving device is constituted by a feature of a pixel portion of a line sensor array or a two-dimensional image sensor array in which a plurality of pixels are provided.

1. (1) P1 = P3,
2. (2) P2 = P4, und
3. (3) Tg1u < Tg1d ≤ Tg2u < Tg2d ≤ Teu < Tg3u < Tg3d ≤ Tg4u ≤ Ted < Tg4d, oder, Teu < Tg3u < Tg3d ≤ Tg4u ≤ Ted < Tg4d < Tg1u < Tg1d ≤ Tg2u < Tg2d,

und schaltet das fünfte Schaltelement EIN und gibt die Photoelektronen an die Ladung-Abgabeeinheit zu einer Zeit ab, wenn alle von den ersten bis vierten Schaltelementen AUS sind. Der Arithmetikprozessor erlangt Luminanzinformationen von dem reflektierten Licht in der Zeitperiode P3 basierend auf einer Differenz zwischen dem Ladungsbetrag Q3, welcher in dem dritten Kondensator gespeichert ist, welcher Umgebungslicht und dem reflektierten Licht entspricht, und dem Ladungsbetrag Q1, welcher in dem ersten Kondensator gespeichert ist, welcher dem Umgebungslicht entspricht, erlangt Luminanzinformation von dem reflektierten Licht in der Zeitperiode Psr basierend auf einer Differenz zwischen dem Ladungsbetrag Q4, welcher in dem vierten Kondensator gespeichert ist, welcher dem Umgebungslicht und dem reflektierten Licht entspricht, und dem Ladungsbetrag Q2, welcher in dem zweiten Kondensator gespeichert ist, welcher dem Umgebungslicht entspricht, bestimmt ein Verhältnis zwischen den Luminanzinformationen von dem reflektierten Licht in der Zeitperiode P3 und den Luminanzinformationen von dem reflektierten Licht in der Zeitperiode Psr, berechnet die Umlaufzeitperiode ΔP basierend auf dem Verhältnis zwischen der Zeitperiode P3 und der Zeitperiode Psr, und misst den Abstand D basierend auf der Umlaufzeitperiode ΔP.[22] A distance measuring device according to a sixth aspect of the present invention includes a light-emitting device that emits pulsed light with respect to an object, a light-receiving device that receives reflected light from the pulsed light, and outputs in response to a received light amount. / Control means which controls the light emitting means and the light receiving means, and an arithmetic processor for calculating a distance to the object by a transit time method using the output of the light receiving means. The light receiving device comprises a photoelectric conversion element which detects the reflected light and converts it into photoelectrons, a charge collecting unit for collecting photoelectrons generated by the photoelectric conversion element, first to fourth capacitors storing the photoelectrons at a predetermined time period, a charge discharge unit which outputs the photoelectrons, first to fourth MOS-type switching elements arranged between the charge collecting unit and the first to fourth capacitors for assigning the photoelectrons to the first to fourth capacitors in synchronism with a pulsed light emission, and a fifth MOS-type switching element disposed between the charge collecting unit and the charge-discharging unit for controlling supply of the photoelectrons from the charge collecting unit to the charge-discharging unit. The photoelectric conversion element includes a first MOS diode having a first electrode formed on a semiconductor substrate with an insulator therebetween, and a plurality of second MOS diodes having second electrodes formed in the semiconductor substrate, wherein the first electrode of the first MOS diode has a comb-like shape, seen from an upper side thereof in which a plurality of branch portions are branched from an electrode portion, and all of the second electrodes of the plurality of second MOS diodes separated from the first electrodes are disposed and each embedded between the plurality of branch portions of the electrode, seen from the top thereof. Assuming that an emission start time of the pulsed light is taken as a time Teu, an emission end time of the pulsed light is taken as a time Ted, an incident end time of the reflected light with respect to the photoelectric conversion element as a time Trd is taken on times from the first to fourth switching elements respectively as times Tg1u . Tg2u . Tg3u . Tg4u OFF times from the first to fourth switching elements each as times Tg1d . Tg2d . Tg3d . Tg4d be taken, a period of time from the time Tg1u by the time Tg1d when P1 is taken, a period of time from the time Tg2u by the time Tg2d when P2 is taken, a period of time from the time Tg3u by the time Tg3d when P3 is taken, a period of time from the time Tg4u by the time Tg4d when P4 is taken, a period of time from the time Tg4u At the time Trd is taken as Psr, an amount of photoelectrons present in the first capacitor within the time period P1 stored as a charge amount Q1 an amount of photoelectrons which are in the second capacitor within the time period P2 stored as a charge amount Q2 an amount of photoelectrons which are in the third capacitor within the time period P3 stored as a charge amount Q3 an amount of photoelectrons which are in the fourth capacitor within the time period P4 stored as a charge amount Q4 is taken, a period of time from a radiation of the pulsed light to the reflection of the pulsed light by the object, and until the reflected light returns, as a round trip period .DELTA.P is taken, and the distance between the object and the light-emitting Device and the light receiving device as a distance D is taken, then the controller controls the radiation of the pulsed light from the light-emitting device and ON / OFF switching of the first to fourth switching elements such that

1. (1) P1 = P3,
2. (2) P2 = P4, and
3. (3) Tg1u <Tg1d ≦ Tg2u <Tg2d ≦ Teu <Tg3u <Tg3d ≦ Tg4u ≦ Ted <Tg4d, or, Teu <Tg3u <Tg3d ≦ Tg4u ≦ Ted <Tg4d <Tg1u <Tg1d ≦ Tg2u <Tg2d,

and turns ON the fifth switching element and outputs the photoelectrons to the charge-dispense unit at a time when all of the first to fourth switching elements are OFF. The arithmetic processor obtains luminance information of the reflected light in the time period P3 based on a difference between the amount of charge Q3 which is stored in the third capacitor, which corresponds to ambient light and the reflected light, and the charge amount Q1 , which is stored in the first capacitor corresponding to the ambient light, obtains luminance information of the reflected light in the period of time Psr based on a difference between the amount of charge Q4 which is stored in the fourth capacitor, which corresponds to the ambient light and the reflected light, and the charge amount Q2 which is stored in the second capacitor, which corresponds to the ambient light, determines a ratio between the luminance information of the reflected light in the time period P3 and the luminance information of the reflected light in the period of time Psr, calculates the round trip period .DELTA.P based on the relationship between the time period P3 and the time period Psr, and measures the distance D based on the round trip period .DELTA.P ,

und die Umlaufzeitperiode ΔP wird berechnet basierend auf der folgenden Gleichung (2), wenn die Zeit Ted später als die Zeit Tg4u ist, $$\mathrm{\Delta }\text{P}=\left[\left(\text{Q}4-\text{Q}2\right)/\left(\text{Q}3-\text{Q}1\right)\right]\times \text{P}3-\left(\text{Ted-Tg4u}\right)$$

[23] In the sixth aspect of the present invention, the round trip period ΔP is calculated based on the following equation (1) when the time Ted and the time Tg4u are the same, $$\mathrm{\Delta }\text{P}=\left\{\left(\text{Q}4-\text{Q}2\right)/\left(\text{Q}3-\text{Q}1\right)\right\}\times \text{P}3$$

and the round trip period ΔP is calculated based on the following equation (2) when the time Ted is later than the time Tg4u is $$\mathrm{\Delta }\text{P}=\left[\left(\text{Q}4-\text{Q}2\right)/\left(\text{Q}3-\text{Q}1\right)\right]\times \text{P}3-\left(\text{Ted Tg4u}\right)$$

[24] In the sixth aspect of the present invention, the controller radiates the pulsed light a plurality of times to the light receiving device in each of respective measuring cycles, and the arithmetic processor calculates the round trip time period .DELTA.P using amounts of charge Q1 to Q4 After photoelectrons have been stored several times in the first to fourth capacitors.

As described above, according to the photoelectric conversion element of the present invention, photoelectrons obtained by photoelectric conversion can be transferred at high speeds to a desired region and collected therein, and a distance measuring device can be realized by applying the principles of a TOF method which can be further applied to various light receiving devices.

Further, according to the light receiving device of the present invention, luminance information can be obtained highly accurately from incident light within a predetermined period of time by using the photoelectric conversion element having the above-mentioned effects, and the light receiving device can be further combined with an electronic shutter function.

Further, according to the light receiving system of the present invention, the S / N ratio can be improved, the influence of

Ambient light interference components can be reduced, and necessary light components can be detected with high accuracy.

Moreover, according to the distance measuring device of the present invention, the S / N ratio can be improved, the influence of ambient light interfering components can be reduced, and the distance to an object can be measured with high accuracy.

list of figures

• 1 Fig. 12 is a view showing a first photoelectric conversion element as viewed from an upper side thereof;
• 2 is a cross-sectional view along a line II-II in 1 ;
• 3 Fig. 10 is a timing chart showing operations of the first photoelectric conversion element;
• 4A to 4C are potential diagrams showing operations (ie operations at times t1 . t2 and t3 in 3 ) of the show first photoelectric conversion element;
• 5 is a potential diagram showing operations (that is, operations at the time t4 in 3 from the first photoelectric conversion element;
• 6 Fig. 12 is a view showing a second photoelectric conversion element viewed from an upper side thereof;
• 7A is a potential diagram along a line VIIA-VIIA in 6 seen;
• 7B is a potential diagram along a line VIIB-VIIB in 6 seen;
• 8th is a potential diagram along a line VIII-VIII in FIG 6 seen;
• 9 is a potential diagram showing operations (that is, operations at the time t4 in 3 ) of the second photoelectric conversion element;
• 10 Fig. 12 is a schematic diagram showing features of the first photoelectric conversion element and the second photoelectric conversion element;
• 11 Fig. 12 is a view showing a first light receiving unit of a first light receiving device, viewed from an upper side thereof;
• 12 Fig. 12 is a view showing a second light receiving unit of a second light receiving device, seen from an upper side thereof;
• 13 Fig. 12 is a schematic diagram showing features of a first light receiving system and a second light receiving system;
• 14 Fig. 10 is a circuit diagram showing a first light receiving unit of the first light receiving system;
• 15 Fig. 10 is a timing chart showing operations of the first light receiving system;
• 16 Fig. 10 is a timing diagram showing basic principles of a technique to reduce the influence of ambient light;
• 17A Fig. 12 is an explanatory diagram showing basic principles of a technique for reducing the influence of ambient light;
• 17B Fig. 12 is an explanatory diagram showing an influence of photon shot noise of sunlight;
• 18A FIG. 4 is an explanatory diagram showing a method to obtain the in 17A to repeat the cycle shown several times, thereby improving the S / N ratio;
• 18B Fig. 10 is an explanatory diagram showing an influence of an arbitrary photon shot noise;
• 19 Fig. 10 is a circuit diagram showing a second light receiving unit of a second light receiving system;
• 20 Fig. 10 is a timing chart showing operations of the second light receiving system;
• 21 Fig. 10 is a schematic diagram showing a first distance measuring device and a second distance measuring device;
• 22 Fig. 12 is a schematic diagram showing a third light receiving unit showing a sensor arrangement of a third light receiving device in the first distance measuring device;
• 23 Fig. 10 is a circuit diagram showing the structure of respective pixels of the third light receiving unit;
• 24 Fig. 10 is a timing chart of a distance measuring cycle;
• 25 Fig. 10 is a timing chart showing an example of irradiation light, reflected light and ON / OFF time settings of first to fifth switching elements within each of respective second collection periods Tca2;
• 26 Fig. 10 is a timing chart showing another example of irradiation light, reflected light and ON / OFF timing of first to fifth switching elements within each of respective second collection periods TCA2 shows;
• 27 Fig. 10 is a circuit diagram showing respective pixels in a fourth light receiving unit of the fourth light receiving device disposed in the second distance measuring device;
• 28 Fig. 10 is a cross-sectional view showing a modified example of a photoelectric conversion element;
• 29 Fig. 12 is a view showing a third photoelectric conversion element viewed from an upper side thereof;
• 30 is a cross-sectional view along a line XXX-XXX in 29 ;
• 31 is a potential diagram showing operations (that is, operations at the time t2 , etc. in 3 ) of the third photoelectric conversion element;
• 32 Fig. 12 is a view showing a fourth photoelectric conversion element viewed from an upper side thereof;
• 33 is a cross-sectional view along a line XXXIII-XXXIII in 32 ;
• 34 Fig. 10 is a potential diagram showing operations of the fourth photoelectric conversion element;
• 35 Fig. 12 is a view showing a fifth photoelectric conversion element viewed from an upper side thereof;
• 36 is a cross-sectional view along a line XXXVI-XXXVI of 35 ;
• 37 Fig. 10 is a timing chart showing operations of the fifth photoelectric conversion element;
• 38A FIG. 13 is a potential diagram illustrating operations (that is, operations at time t11 in FIG 37 ) of the fifth photoelectric conversion element;
• 38B Fig. 13 is a similar potential diagram of operations at time t12;
• 38C is another potential diagram showing operations at time t11;
• 39 Fig. 12 is a view showing a sixth photoelectric conversion element viewed from an upper side thereof;
• 40A is a potential diagram along a line XLA-XLA in 39 ;
• 40B is a potential diagram view along a line XLB-XLB in 39 ;
• 41 is a potential diagram view along a line XLI-XLI in 39 ;
• 42 Fig. 12 is a view showing a seventh photoelectric conversion element viewed from an upper side thereof; and
• 43 is a potential diagram view along a line XLIII-XLIII in 42 ,

Description of embodiments

A photoelectric conversion element, a light emitting device, a light receiving system and a distance measuring device according to embodiments of the present invention will be described below with reference to FIGS 1 to 43 to be discribed.

[First photoelectric conversion element 10A ]

First, as in the 1 and 2 includes a photoelectric conversion element (hereinafter referred to as a first photoelectric conversion element 10A denotes) according to a first embodiment of the present invention, a first MOS diode 18a which is a first electrode 16a that's on a semiconductor base 12 (please refer 2 ) with an insulator arranged therebetween 14 is formed, and a plurality of second MOS diodes 18b , which second electrodes 16b have on the semiconductor base body 12 with an insulator arranged therebetween 14 are formed. In particular, such as in 2 shown is the semiconductor base body 12 is formed by a p-type impurity diffusion region. In addition, the above-mentioned first MOS diode 18a and the second MOS diodes 18b made by the first electrode 16a and the second electrodes 16b of silicon or a metallic conductor or the like on the semiconductor base body 12 over an insulation layer (insulator 14 ) made of SiO ₂ or the like can be formed.

As seen from the top, the first electrode has 16a from the first MOS diode 18a a comb-like shape in which a plurality of branching portions 12 each from an electrode section 20 branch. The second electrodes 16b from the second MOS diodes 18b are each arranged to be between the plurality of branch portions 22 from the first electrode 16a to be embedded. The branching sections 22 from the first electrode 16a in the first MOS diode 18a and the second electrodes 16b from the second MOS diodes 18b are each rectangular shaped.

A cargo collection unit 26 to collect photoelectrons emitted from the first photoelectric conversion element 10A is generated on a base section 24 (substantially in the middle in the longitudinal direction) of the one electrode portion 20 on the first electrode 16a educated. The cargo collection unit 26 is designed to stand out from the base section 24 from the one electrode section 20 in an opposite direction to the branching sections 22 to extend. The cargo collection unit 26 structurally within the first photoelectric conversion element 10A be included or may not be included.

First power supply connections 28a from each of the branching sections 22 from the first electrode 16a in the first MOS diode 18a and second power supply terminals 18b from each of the second electrodes 16b from the second MOS diodes 28b are formed at positions which are maximum of the charge collecting unit 26 are separated, as seen from the top. In particular, the first and second Power supply terminals 28a . 28b at ends coming from the charge collection unit 26 are spaced from each of the branching sections 22 educated.

In addition, unillustrated metal wires are provided which provide a first voltage V1 to the first power supply connections 28a create, and a second voltage V2 respectively and independently to the second power supply terminals 28b invest.

The first tension V1 is via a voltage in the L range or a low voltage level V1L to a voltage in the H range or a high level voltage V1H changed while the second tension V2 via a voltage in the L range or a low voltage level V2L to a voltage in the H range or a high level voltage V2H is changed. The size ratio of the levels is such that at least V1H > V2H , The relation between V1L and V2L may be such that they are the same or that V1L > V2L , Furthermore, the low-voltage voltages V1L and V2L Zero level voltages 0V or negative voltages.

Operations of the first photoelectric conversion element 10A should be with reference to the timing diagram of 3 and the potential diagrams of 4A to 4C and 5 be explained. How intuitively understandable is the fact that the potential diagrams of the 4A to 4C and 5 on photoelectrons 30 are applicable as charges, it is shown that the potential sites 32 get lower as the potentials go higher.

First are at a time t1 in 3 due to the fact that the first tension V1 and the second tension V2 both at the low-voltage levels V1L and V2L are, as in 4A shown the potential points 32a below the first electrode 16a and the potential points 32b below the second electrodes 16b essentially the same.

After that, when the first voltage V1 to the high level V1H goes and the second tension V2 to the high level V2H goes, as in 4B shown are the potential sites 32a below the first electrode 16a and the potential points 32b below the second electrodes 16b both lowered, but due to the fact that V1H > V2H , are the potential places 32a below the first electrode 16a lower than the potential sites 32b below the second electrodes 16b , In other words, it becomes a potential gradient 34 formed in which the potential spot at the locations below the second electrodes 16b to locations thereof below the first electrode 16a gets lower. Consequently, photoelectrons become 30 , which are below the second electrodes 16b to be brought to positions below the first electrode 16a to migrate, and in particular to positions below the plurality of branching sections 22 from that.

After that, at the moment t3 if only the second voltage V2 on the Niederniveauspension V2L goes, as in 4C shown, only the potential sites 32b below the second electrodes 16b high, causing the potential gradient 34 becomes steeper, and thus the photoelectrons become 30 below the second electrodes 16b brought at high speeds among the plurality of branching sections 22 from the first electrode 16 to wander.

If after that at the time t4 the voltage V1 a low voltage level V1 L becomes, as in 5 shown, though potential spots 32a below the first electrode 16a increase, due to the fact that the first power supply connections 28a from the first electrode 16a are formed at positions, which of the charge collecting unit 26 are maximally separated, below the potential sites 32a below the first electrode 16a , the potential points rise 32a at portions thereof directly below the first power supply terminals 28a rapidly, whereas potential sites 32a closer to the cargo collection unit 26 gradually increase. As a result of sinking the positive charge from the first electrode 16a by having the potential at portions just below the first power supply terminals 28a is lowered, and by the potential over the entirety of the first electrode 16a is temporarily lowered, the potential points rise 32a below the first electrode 16a in the level. Consequently, potential gradients also become 34 in the longitudinal direction below the branch sections 22 from the first electrode 16a trained and with time the potential gradients move 34 parallel to the charge collection unit 26 , causing the photoelectrons 30 be caused to travel at high speeds to the charge collection unit 26 to wander.

In this way, in the first photoelectric conversion element 10A by attaching to the first electrode 16a applied first voltage V1 and to the second electrodes 16b applied voltage V2 is controlled / regulated, potential gradients 34 by a difference in the potential sites which are below the adjacent first electrode 16a and the second electrodes 16b are formed, formed. Therefore, photoelectrons obtained by photoelectric conversion 30 transferred at high speeds and effective in the cargo collection unit 26 to be collected, without the appearance of residual charges remaining below the electrodes.

In addition, since the first power supply connections 28a from the first electrode 16a are formed at positions, which of the charge collecting unit 26 are maximally separated, are the Potentialstellen 32a below the first electrode 16a able to continuously as starting points of sections directly below the first power supply connections 28a to be raised. According to a raising of potential spots 32a below the first electrode 16a electric fields are generated, and the photoelectrons 30 below the first electrode 16a can be moved at high speeds. As a result, photoelectrons can 30 below the first electrode 16a For example, the photoelectrons 30 below the plurality of branching points 22 , be made to move quickly to the cargo collection unit 26 to move (wander).

[Second photoelectric conversion element 10B ]

Next, a photoelectric conversion element (hereinafter referred to as a second photoelectric conversion element 10B designated) according to a second embodiment with reference to the 6 to 9 to be discribed.

As in 6 has the second photoelectric conversion element 10B substantially the same structure as the above-mentioned first photoelectric conversion element 10A , except that the forms of the first electrode 16A and the second electrodes 16b are different, especially seen from the top of it.

In particular, each of the branching sections has 22 from the first electrode 16a such a shape that the electrode width thereof gradually becomes the one electrode portion 20 extended, viewed from the top, and all of the second electrodes 16b have such a shape that the electrode width thereof gradually becomes the one electrode portion 20 from the first electrode 16a narrowed, seen from the top.

In the case of potential spots 32a below the first electrode 16a be focused and considered as in the 7A and 7B As shown, the portion thereof where the electrode width is narrow receives an influence from the surface potential of the semiconductor base body 12 (Silicon substrate), and the potential spot 32a1 in this portion is high, whereas the potential spot 32c2 is low from the portion where the width is wide. Consequently, as in 8th shown are the potential sites 32a from the branch sections 22 from the first electrode 16 lower as the width gets wider, and gradually become the one section 20 inclined downwards.

As a result, is currently migrating t4 in 3 when the first voltage V1 the Niederniveauspension V1L although, as mentioned above, the potential sites 32a at sections directly below the first power supply connections 28a rise rapidly and potential spots 32a closer to the cargo collection unit 26 gradually increase, at this time, as in 9 shown because the potentials 32a down to the one electrode section 20 inclined, the photoelectrons 30 faster to the cargo collection unit 26 ,

[First light receiving device 100A ]

Next, a light receiving device (hereinafter referred to as a first light receiving device 100A referred to) according to a first embodiment with reference to the 10 and 11 be explained.

As in 10 shown comprises the first light receiving device 100A a lens 102 and a first light receiving unit 104A , Incident light La, which passes through the lens 102 happens, is on the first light receiving unit 104A focused. The Lens 102 may also comprise a plurality of lenses arranged in a line or in a matrix.

As in 11 shown includes the first light receiving unit 104A a photoelectric conversion element 10 , a cargo collection unit 26 to collect photoelectrons emitted from the photoelectric conversion element 10 to generate a capacitor Ca to store photoelectrons at a predetermined time period, a charge-dispense unit 108 , which emits the photoelectrons, a first switching element SW1 which is between the cargo collection unit 26 and the capacitor Ca is arranged to cause the in the charge collecting unit 26 collected photoelectrons to the capacitor Ca, and a second switching element SW2 which is between the cargo collection unit 26 and the charge-dispensing unit 108 is arranged to release a photoelectron from the charge collection unit 26 to the charge-dispensing unit 108 to control. The cargo dispensing unit 108 is arranged to face the capacitor Ca while receiving the charge collecting unit 26 intervening. With this embodiment, in particular, the capacitor Ca and the charge-discharge unit 108 at symmetrical positions with respect to the center of the charge collecting unit 26 arranged. The capacitor Ca is formed by an MIM capacitor, a MOS capacitor, an embedded photodiode structure or a parasitic pn junction capacitance.

The above-mentioned first photoelectric conversion element 10A and the second photoelectric conversion element 10B are in the photoelectric conversion element 10 used. In 11 an example is shown in which the first photoelectric conversion element 10A as the photoelectric conversion element 10 is used.

The first switching element SW1 includes a gate electrode which is between the charge collection unit 26 and the capacitor Ca, an insulating body below the gate electrode, and a MOS structure formed in the semiconductor base body 12 is formed below the insulating body. The second switching element SW2 includes a gate electrode which is between the charge collection unit 26 and the charge-dispensing unit 108 is disposed, an insulating body below the gate electrode, and a MOS structure, which in the semiconductor base body 12 is formed below the insulating body. Consequently, the first switching element SW1 and the second switching element SW2 Turned ON by applying high-level voltages to the gate electrodes and turned OFF by low-level voltages (which are a zero-level voltage 0V or a negative voltage) may be applied to the gate electrodes.

At least the charge collection unit 26 , the capacitor Ca, the first switching element SW1 and the second switching element SW2 are formed in a light-shielded region Z.

When the first light receiving device 100A is used, first, light incident within a period of time (hereinafter referred to as a "valid period") during which it is desired to obtain luminance information of specified incidental light La becomes photoelectrons in the photoelectric conversion element 10 converted, and the photoelectrons are at high speeds in the charge collection unit 26 transferred and collected according to the above operations. Thereafter, by turning on the first switching element SW1 the photoelectrons from the charge collection unit 26 transferred to the capacitor Ca, and luminance information of the incident light La are obtained based on the amount (charge amount) of photoelectrons, which are transferred to the capacitor Ca. Then, after elapse of a predetermined time period, the first switching element becomes SW1 Switched off.

On the other hand, unnecessary light incident outside the valid period is also applied to the photoelectric conversion element 10 converted into photoelectrons and such photoelectrons are at high speeds in the charge collection unit 26 transferred and collected according to the above operations. Thereafter, by turning ON the second switching element SW2 the unnecessary photoelectrons from the charge collection unit 26 to the charge-dispensing unit 108 transferred and submitted from there. Then, after elapse of a predetermined period of time, the second switching element becomes SW2 Switched off.

Incidentally, as a method to improve the S / N ratio of the luminance information, there is a method in which a plurality of valid periods are set and photoelectrons are obtained during such a given period of time, which are obtained within such valid periods. In particular, by setting the valid period short, it is considered that the influence of ambient light can be eliminated. For example, a plurality of periods or cycles are set within a predetermined period of time, each of such cycles being less than 100μs, and further, valid periods are set within each of the cycles, respectively, with the duty cycle of each of the valid periods being made short.

When this method is used, it is necessary that the photoelectrons present in the photoelectric conversion element 10 photoelectrically converted at high speeds to a node (that is, a region where the photoelectrons are converted into electrical signals). In particular, in order to obtain a high S / N ratio, a photoelectric conversion element having a large light receiving area is required. However, in the case where a photoelectric conversion element having a large light receiving area is used, the distance to the node is long, and hence it is difficult for the photoelectrons to be transferred at high speeds to the node. For example, when a case is considered and explained in which a conventional photoelectric conversion element (a conventional photoelectric conversion element) is provided and in the first light receiving device 100A is used, then in the case that the time during which the first switching element SW1 ON, which is about a few hundred ns, is the first switching element SW1 Turned off before the photoelectrons, which in the photoelectric Conversion element photoelectrically converted and obtained in this, at the first switching element SW1 arrive, and thus the photoelectrons through the first switching element SW1 not transferred to the capacitor. Consequently, the photoelectrons are transmitted through the second switching element SW2 transferred to the charge-dispensing unit and are delivered by this.

Further, in the conventional art, a structure is provided (with reference to the above-mentioned document 1 ) in which photoelectrons from a photoelectric conversion element are each assigned two nodes by separate paths. In such a case, due to the fact that the positions and the lengths from the electrodes (gate electrodes) to each other differ from each other, a difference occurs in the transfer efficiency to each of the nodes, resulting in a reduction in S / N ratio, which is caused by the existence of a distribution in the in-plane conversion efficiency of the photoelectric conversion element or differences in the transfer paths from the photoelectrons.

Thus, in the first light receiving device 100A the above-mentioned first photoelectric conversion element 10A or the second photoelectric conversion element 10B as the photoelectric conversion element 10 used. In this case, because potential gradients 34 in the photoelectric conversion element 10 are formed, it is possible that the photoelectrons are transferred at high speeds by electric fields, whereby photoelectrons, which are obtained in the valid period, to the capacitor Ca through the first switching element SW1 can be transferred. Of course, the photoelectrons can also be at high speeds using the second photoelectric conversion element 10B as the photoelectric conversion element 10 be transferred.

Consequently, the first light receiving device 100A in applications where it is necessary to obtain a high S / N ratio, and is suitable, for example, for cases in which the light-receiving area is large and / or the distance of the nodes from which the photoelectrons are output , is long. In addition, since charges in a charge collection unit 26 are collected and the capacitor Ca and the charge-discharge unit 108 at symmetrical positions with respect to the center of the charge collection unit 26 Even if the photoelectrons are assigned to two or more nodes, the transfer paths from the electrons are the same, and thus, differences in the transfer efficiency to each of the nodes do not occur.

[Second light receiving device 100B ]

Next, a light receiving device (hereinafter referred to as a second light receiving device 100B designated) according to the second embodiment with reference to the 10 and 12 be explained.

As in 10 shown comprises the second light receiving device 100B similar to the above-mentioned first light receiving device 100A , a lens 102 and a second light receiving unit 104B ,

The second light receiving unit 104B has approximately the same structure as that of the above-mentioned first light receiving unit 104A from the first light receiving device 100A , However, as in 12 As shown, the second light receiving unit differs 104B of which is that a first capacitor Ca1 and a second capacitor Ca2 are included to store photoelectrons each at predetermined time periods.

In particular, the charge delivery unit 108 arranged so as to be the photoelectric conversion element 10 faces while the cargo collection unit 26 is arranged in between, whereas the first capacitor Ca1 and the second capacitor Ca2 are arranged so that they face each other while the charge collecting unit 26 is recorded in between. In the present embodiment, in particular, the first capacitor Ca1 and the second capacitor Ca2 at symmetrical positions with respect to the center of the charge collection unit 26 arranged.

Furthermore, a first switching element SW1 which is between the cargo collection unit 26 and the first capacitor Ca1 is arranged to cause in the charge collection unit 26 collected photoelectrons to the first capacitor Ca1 wander, a second switching element SW2 which is between the cargo collection unit 26 and the second capacitor Ca2 is arranged to cause in the charge collection unit 26 collected photoelectrons to the second capacitor Ca2 wander, and a third switching element SW3 which is between the cargo collection unit 26 and the charge-dispensing unit 108 is arranged to release a photoelectron from the charge collection unit 26 to the charge-dispensing unit 108 to control.

The first capacitor Ca1 and the second capacitor Ca2 are from a MIM capacitor or a MOS capacitor or an embedded photodiode structure or a parasitic pn junction capacitance.

The first switching element SW1 includes a MOS structure formed by a gate electrode which is sandwiched between the charge collection unit 26 and the first capacitor Ca1 is disposed, an insulating body under the gate electrode, and the semiconductor base body 12 under the insulating body. The second switching element SW2 includes a MOS structure formed by a gate electrode which is sandwiched between the charge collection unit 26 and the second capacitor Ca2 is disposed, an insulator under the gate electrode and the semiconductor base body 12 under the insulating body. The third switching element SW3 includes a MOS structure formed by a gate electrode which is sandwiched between the charge collection unit 26 and the charge-dispensing unit 108 is disposed, an insulating body under the gate electrode, and the semiconductor base body 12 under the insulating body. As a result, the first to third switching elements become SW1 to SW3 Turned ON by applying a high level voltage to the gate electrodes thereof and turned OFF by applying a low level voltage (which is a zero level voltage 0V or a negative voltage) may be applied to the gate electrodes thereof.

At least the charge collection unit 26 , the first capacitor Ca1 , the second capacitor Ca2 and the first to third switching elements SW1 to SW3 are formed in a light-shielded region Z.

The second light receiving device 100B is advantageous because due to the fact that the first capacitor Ca1 and the second capacitor Ca2 therein, a disturbance of ambient light can be removed from the obtained luminance information.

Specifically, light incident in a period (hereinafter referred to as a "first valid period") during which it is desired to obtain luminance information of ambient light as disturbance information is included in the photoelectric conversion element 10 converted into photoelectrons, and such photoelectrons are transmitted at high speeds and in the charge collection unit 26 collected, according to the above operations. Thereafter, by turning ON the first switching element SW1 the photoelectrons in the charge collection unit 26 to the first capacitor Ca1 is transferred and luminance information of ambient light is obtained based on the amount (charge amount) of photoelectrons which are to the first capacitor Ca1 were transferred. Then the first switching element SW1 is turned OFF after a lapse of a predetermined period of time.

Next, light incident in a period (hereinafter referred to as a "second valid period") during which it is desired to obtain luminance information of specific incident light La is formed in the photoelectric conversion element 10 converted into photoelectrons and such photoelectrons are transmitted at high speeds and in the charge collection unit 26 collected according to the above operations. Thereafter, by turning ON the second switching element SW2 the photoelectrons in the charge collection unit 26 to the second capacitor Ca2 and luminance information of specific incident light La is obtained based on the amount (charge amount) of photoelectrons which are to the second capacitor Ca2 were transferred. Then, after elapse of a predetermined time period, the second switching element becomes SW2 Switched off. Since disturbance information due to ambient light is contained within the obtained luminance information of the specific incident light, luminance information can be obtained from which disturbances caused by ambient light have been removed, by deriving therefrom the luminance information from the ambient light transmitted through the first capacitor Ca1 was obtained, to be subtracted.

On the other hand, light incident outside the first valid period and the second valid period also becomes photoelectrons in the photoelectric conversion element 10 and such photoelectrons are transmitted at high speeds and in the charge collection unit 26 collected according to the above operations. Therefore, by turning ON the third switching element SW3 the photoelectrons in the charge collection unit 26 to the charge-dispensing unit 108 transferred and submitted from there.

Since the first photoelectric conversion element 10A or the second photoelectric conversion element 10B also as the photoelectric conversion element 10 in the second light receiving device 100B can be used, photoelectrons, which are obtained in the first valid period, at high speeds to the first capacitor Ca1 through the first switching element SW1 can be transferred, and photoelectrons, which are obtained in the second valid period, can at high speeds to the second capacitor Ca2 through the second switching element SW2 be transferred. In addition, the first capacitor Ca1 and the second capacitor Ca2 at symmetrical Positions with respect to the center of the cargo collection unit 26 arranged.

Consequently, also in the second light receiving device 100B the same effects as those in the first light receiving device 100A offered. Further, since noise components due to ambient light can be removed, luminance information of specific incident light La can be obtained very accurately and the S / N ratio can be improved.

[First light receiving system 200A ]

Next, a light receiving system (hereinafter referred to as a first light receiving system 200A referred to) according to a first embodiment with reference to the 13 to 15 to be discribed. In the 14 and 15 designated V1 a tension V1 in the case of the first photoelectric conversion element 10A or a first voltage in the case of the second photoelectric conversion element 10B , and V2 denotes a second voltage in the case of the second photoelectric conversion element 10B ,

As in 13 shown includes the first light receiving system 200A a light-emitting device 202 , the above-mentioned first light receiving device 100A , a control device 204 , an arithmetic processor 206 , and a first power supply 208A and a second power supply 208B for supplying predetermined power supply voltages to the light-emitting device 202 , the first light receiving device 100A , the controller 204 and the arithmetic processor 206 , For simplicity, was in 13 an illustration of power source lines to each of the devices from the first power supply 208A and the second power supply 208B omitted.

In the first light receiving system 200A becomes pulsed light Lp emitted from the light-emitting device 202 is radiated, reflected by an object W and is brought to the first light receiving device 100A to hit or fall into this. To facilitate explanation, the pulsed light Lp should be from the light-emitting device 202 to the object W as the irradiation light Le and the pulsed light from the object W to the first light receiving means 100A should be referred to as reflected light Lr.

The control device 204 performs a control to obtain components of reflected light Lr from the object W, from the light received from the light receiving device 100A Will be received.

<Light-emitting device 202 >

The light-emitting device 202 includes a light emitter 210 , which pulsed light based on a command from the controller 204 outputs. In the first light receiving system 200A includes the light emitter 210 from the light-emitting device 202 stacked (serially connected) semiconductor laser bars consisting of light emitting points (emitters) arranged in a linear shape allowing surface light emission thereof.

The light emitter 210 is able to emit infrared light with a wavelength of 870 nanometers [nm] at an output power of 100 watts [W]. Further, in each cycle Cm (periods in which measurement values are determined), an exposure process (electric charge collection process) is performed multiple times (see 24 ). Suppose that the period of the exposure process (with reference to the second collection period Tca2 in FIG 24 ) Is 100 microseconds, gives the light emitter 210 pulsed light Lp for an output time (pulse width) of 100 nanoseconds. In other words, the light emitter 210 operated with a duty cycle of 0.1%.

The light emitter 210 may include a linear array of light emitting points, or may include a plurality of light emitting points arranged in a matrix form. As the light emitting element, a laser diode, a light emitting diode (LED), etc. or other types of light emitting elements may be used. Furthermore, the pulsed light Lp emitted by the light emitter 210 has a different wavelength, for example, a wavelength which is longer than 700 nm and shorter or equal to 1050 nm. Furthermore, the output from the light emitter 210 a value other than that described above, for example, a value greater than 20 W and less than or equal to 10 kW. In addition, the pulse width of the pulsed light Lp may be another length, for example, a length equal to or greater than 10 nanoseconds and less than or equal to 1 millisecond. In addition, the duty cycle with which the light emitter 210 operated, have a different value, for example, a value greater than or equal to 0.01% and less than or equal to 1%.

<First light receiving device 100A >

Since the first light receiving device 100A has already been described above, multiple descriptions thereof are omitted, however, should now the first light receiving device 100A and in particular the first light receiving unit 104A with reference to 14 be explained in terms of their circuit structure.

In particular, as in 14 shown includes the first light receiving unit 104A the above-mentioned photoelectric conversion element 10 , the cargo collection unit 26 , the capacitor Ca, the charge-dispense unit 108 , the first switching element SW1 and the second switching element SW2 while additionally comprising a reset switch SR and an amplifier AP.

(First switching element SW1 , Capacitor Ca)

The first switching element SW1 is formed for example by an n-channel MOS transistor, wherein the source (source) with the charge collecting unit 26 is connected, the drain (drain) connected to the capacitor Ca and the gate (control electrode) is connected to a gate driver circuit, not shown. Consequently, by selectively controlling ON / OFF states of the first switching element in accordance with a gate drive signal (readout signal Sg) from the gate drive circuit applied to the gate, in the charge collection unit 26 lying photoelectrons are transferred to the capacitor Ca.

(Second switching element SW2 , Charge-dispensing unit 108 )

The second switching element SW2 is formed for example by an n-channel MOS transistor, wherein the source with the charge collecting unit 26 connected to the drain with the charge-discharge unit 108 is connected and a positive power source voltage Vdd from the first power source 208A the charge-dispensing unit 108 is supplied. Further, a not shown gate driver circuit is connected to the gate. Thus, by supplying a gate drive signal (charge output signal Se) from the gate drive circuit to the gate (that is, raising the voltage supplied to the gate to a high level), the gate can be turned ON, whereby the in the cargo collection unit 26 lying photoelectrons through the charge-discharge unit 108 are discharged without being transferred to the capacitor Ca.

(Reset switch SR)

The reset switch SR is formed by an n-channel MOS transistor, wherein a contact point between the first switching element SW1 and the capacitor Ca is connected to the source, and a reset voltage Vr from the second power source 208B the drain is supplied. Further, a not shown gate driver circuit is connected to the gate. Thus, by turning ON the reset switch SR as a result of the gate drive circuit supplying a drive signal (reset signal Sr) to the gate, the potential of the capacitor Ca can be set at a constant reset potential. In other words, the capacitor Ca can be reset.

(Amplifier AP)

The amplifier AP comprises an output element TR, which is formed for example by an n-channel MOS transistor, and an output switch SEL, which is formed for example by an n-channel MOS transistor, which is connected between a source of the output element TR and an output line 212 connected. A contact point a1 between the first switching element SW1 and the capacitor Ca is connected to the gate of the output element TR, a power source voltage Vdd from the first power source 208A is supplied to the drain, and a drain from the output switch SEL is connected to the source of the output element TR. An unillustrated gate driver circuit is connected to the gate of the output switch SEL and the output line 212 is connected to the source of the output switch SEL.

Consequently, by turning ON the output switch SEL by supplying a gate drive signal (output selection signal Ss) from the gate drive circuit with respect to the gate from the output switch SEL, a voltage corresponding to the photoelectrons (charge amount Q) included in the capacitor Ca are amplified in the output element TR and is interrogated as an output voltage Vout.

<Operations of the first light receiving system 200A >

Next, operations of the first light receiving system will be described 200A with reference to 15 explained. In 15 is V1 shown as a second voltage applied to the second electrode 16b in the same way as the first tensions V1 . V2 , which are connected to the first electrode 16a from the photoelectric conversion element 10 (first photoelectric conversion element 10A and second photoelectric conversion element 10B) be created. The light emission time of the pulsed light Lp from the light-emitting device 202 is designated by WL, whereas time periods during which the first switching element SW1 and the second switching element SW2 Are ON, each with WD1 . WD2 are designated.

First, the controller drives 204 from the first light receiving system 200A the light-emitting device 202 at each of fixed periods (cycles), so that within each cycle, the pulsed light Lp is irradiated for a light emission time WL. Pulsed light Lp (radiation light Le) emitted from the light-emitting device is reflected by the object W and is applied to the first light-receiving device 100A as reflected light Lr impinge. The light which is on the first light receiving device 100A is incident through the photoelectric conversion element 10 converted into photoelectrons, which at high speeds to the charge collection unit 26 be transmitted.

The first switching element SW1 transfers the photoelectrons leading to the charge collection unit 26 were transferred to the capacitor Ca. Specifically, photoelectrons which are transferred to the capacitor Ca are photoelectrons (charge amount Q) obtained by photoelectric conversion from the reflected light Lr. Consequently, information regarding the intensity of the reflected light can be obtained by the charge amount Q.

Further, in the case that the first switching element SW1 is not ON, the photoelectrically converted photoelectrons are regarded as unnecessary photoelectrons, and thus, by turning ON the second switching element, such unnecessary photoelectrons can be supplied to the charge-dispense unit 108 be delivered.

Detailed operation time settings from the first light receiving system 200A be referring to 15 explained.

First, output settings are from the first light receiving system 200A made, the second switching element SW2 and the reset switch SR are both turned ON, and the first switching element SW1 and the output switch SEL are both turned OFF. Due to this, unnecessary photoelectrons are generated in the photoelectric conversion element 10 are stored, along with the setting of the potential of the capacitor Ca to the reset potential Vr. Thereafter, the reset switch SR is turned OFF.

After the initial adjustments are completed, the cycle is performed only once, or alternatively repeated several times to obtain the intensity of the reflected light.

As in 15 is shown, in each cycle to an initial time t1 a light pulse Lp from the light-emitting device 202 according to a drive of the light-emitting device 202 by the controller 204 broadcast. Thus, at a time t1 the second switching element SW2 OFF, whereas the first switching element SW1 Is turned ON (while the second switching element SW2 OFF-stays) from the time t1 and by the readout time period WD1 , Further, by the time t1 the first tension V1 and the second tension V2 , which is the first electrode 16a and the second electrode 16b from the photoelectric conversion element 10 be fed, each at high levels VH1 and VH2 set. Due to this, the photoelectrons are formed by photoelectric conversion by the photoelectric conversion element 10 can be obtained, below the first electrode 16a and the second electrode 16b collected, and a part of the photoelectron migrates to the charge collecting unit 26 , and are further by the first switching element SW1 transferred to the capacitor Ca. After the irradiation time period WL of the pulsed light Lp has occurred, the second voltage is obtained at the second time t2 a low level V2L such that according to the potential gradient formed thereby 34 the photoelectrons below the second electrode 16b at high speeds to locations below the first electrode 16a be transferred, and at a time t3 after that receives the first voltage V1 on a low level V1L , the photoelectrons below the first electrode 16a become the charge collection unit at high speeds 26 are transferred and then to the capacitor Ca through the first switching element SW1 transferred.

After that, at a time t4 the first switching element SW1 OFF, and of a time t4 and over a period of time (charge-discharge period WD2 ) until initialization from the next cycle, becomes the second switching element SW2 ON (while the first switching element SW1 OFF remains). Due to this, unnecessary photoelectrons are generated in the photoelectric conversion element 10 during the charge-discharge period WD2 were generated by the second switching element SW2 and the charge-dispensing unit 108 issued. Likewise in the charge-discharge period WD2 become the first tension V1 and the second tension V2 , which is the first electrode 16a and the second electrode 16b from the photoelectric conversion element 10 be supplied in a similar manner as during the period WD1 controlled, whereby photoelectrons, which from the photoelectric conversion element 10 be generated, which is the first electrode 16a and the second electrode 16b encompassed by the charge delivery unit 108 are discharged, so that no charges in the photoelectric conversion element 10 stay.

In a phase after completion of a predetermined number of cycles, by turning ON the output switch SEL, in the output line 212 a voltage corresponding to the photoelectrons (charge amount) stored in the capacitor Ca is amplified in the output element TR and output as an output voltage Vout. The output voltage Vout is digitally converted by an A / D converter, not shown, and is then sent to the arithmetic processor 206 fed.

[Second light receiving system 200B ]

Next, a light receiving system (hereinafter referred to as a second light receiving system 200B designated) according to a second embodiment with reference to the 13 and 16 to 20 to be discribed. In the 19 and 20 designated V1 a tension V1 in the case of the first photoelectric conversion element 10A , or a first voltage in the case of the second photoelectric conversion element 10B , and V2 denotes a second voltage in the case of the second photoelectric conversion element 10B ,

The second light receiving system 200B has substantially the same structure as the above-mentioned first light receiving system 200A However, as in 13 shown the second light receiving system 200B of which is that the second light receiving device 100B is used, so that a control / regulation by the control / regulating device 204 is performed to components of ambient light Ls, which of the second light receiving device 100B is received, and to obtain components of reflected light Lr from the object W, whereby information about the intensity of reflected light which is not dependent on ambient light Ls can be obtained.

<Basic principles for reducing the influence of ambient light Ls>

Basic principles for reducing the influence of ambient light Ls, and in particular, basic principles in the case of using continuous light, will be described below with reference to FIGS 16 to 18B described.

First, as in 16 shown within an initial one frame period F1 Photoelectrons are taken at a time in which continuous light is not radiated on the object W, and a luminance value of the photoelectrons during a non-irradiated time is obtained. In the next second frame period F2 For example, photoelectrons are picked up at a time in which continuous light is irradiated to the object W, and a luminance value from the photoelectrons during a broadcasting time is obtained. Then, by obtaining a difference in the luminance values thereof, the influence of ambient light (mainly light components of sunlight) can be reduced. In the case that a cycle is formed by the first frame period F1 and the second frame period F2 Combined, the duty cycle of continuous light with respect to the one cycle is 50%. Further, as a frame period 1 / 60 Seconds, which embodies the image acquisition period by an imaging device.

Additionally, in the initial one frame period F1 Receive light without emitting continuous light, whereas in the following second frame period F2 due to the fact that light is received during continuous light over the second frame period F2 is emitted, caused by ambient light interference components also over the first frame period F1 and the second frame period F2 be recorded.

Consequently, as in 17A is shown, the luminance value (sunlight component) from the first frame period F1 from the luminance value (signal component + sunlight component) from the second frame period F2 in order to ideally eliminate the influence of the sunlight component, and to obtain only the signal component.

However, in an environment where intense ambient light such as sunlight is present, there is also an effect of photon shot noise, and in addition, due to the fact that such photon shot noise is of an arbitrary nature, the influence of ambient light may not be sufficient can be eliminated by merely calculating the difference in the above-mentioned luminance values. In particular, as in 17B in the case that a photon shot noise component occurring in the first frame period F1 is different from the photon shot noise component which is generated in the second frame period F2 is generated, the difference therebetween is added to the signal component.

Further, in an environment where intense ambient light such as sunlight is present, for example, as in FIG 17A Due to the fact that the sunlight component is stronger than the signal component (that is, the S / N ratio of the signal component is low), a problem arises in that Input dynamic range of the signal component is small. In a conventional imaging element, the valid range (dynamic range) of output signals with respect to the amount of incident light is limited, so that when sunlight is irradiated or incident, it is recognized that adverse effects are caused, such as the signal output becoming saturated , Consequently, such as in 18A is shown a cycle (that is, exposure operations during the one frame period F1 and the second frame period F2 and subtracting the luminance value (sunlight component) from the first frame period F1 from the luminance value (signal component + sunlight component) from the second frame period F2 ) is repeated several times, and signal components are accumulated, thereby believing that the S / N ratio of the signal component can be improved. However, as stated above (see 17B) In each of the frame periods, an arbitrary photon shot noise is inserted and, in addition, such arbitrary photon shot noise also partially persists in the difference calculation. Therefore, as in 18B 1, a problem arises that signal components are accumulated and also accumulated together with these other interference components, so that after the difference calculation, the S / N ratio is disadvantageously reduced.

In order to improve the S / N ratio of the signal component, it may be thought to increase the energy of the continuous light. However, due to the fact that continuous light is emitted over a frame period, a new problem leads to the generation of heat and energy consumption tends to increase. For example, although regarding the heat generation, a cooling mechanism may be separately provided in response thereto, additional problems arise that the manufacturing cost and operating cost of the light receiving system become higher, and the size of the light receiving system increases. Consequently, there is a limit to how much the energy from the continuous light can be increased.

On the other hand, with the above-mentioned light-emitting device 202 because pulsed light Lp with a short pulse width and a high output power from the light emitter 210 is emitted in the second light receiving system 200B in which the light-emitting device 202 is used to solve the various problems caused by continuous light as mentioned above.

[Details of Second Light Receiving System 200B]

<Light emitting device 202>

The light-emitting device 202 has substantially the same structure as the light-emitting device 202 from the first light receiving system 200A and therefore explanations thereof are omitted.

<Second Light Receiving Device 100B>

Since the second light receiving device 100B already above (see 12 ), repeated explanations thereof are omitted. However, using 19 the second light receiving device 100B be explained in terms of their circuit structure.

In particular, as in 19 shown comprises the second light receiving device 100B the above-mentioned photoelectric conversion element 10 , the cargo collection unit 26 , a first capacitor Ca1 , a second capacitor Ca2 , the cargo-dispensing unit 108 , and the first to third switching elements SW1 to SW3 , and further comprises a first reset switch SR1 , a second reset switch SR2 , a first amplifier AP1 and a second amplifier AP2 ,

(First switching element SW1, first capacitor Ca1)

The first switching element SW1 is formed for example by an n-channel MOS transistor, wherein the charge collecting unit 26 connected to the source, the drain to the first capacitor C1 is connected and the gate is connected to a not shown gate driver circuit. Consequently, a control is performed to the first switching element SW1 selectively ON and OFF, according to the gate drive signal (first read-out signal sg1 ) from the gate drive circuit with respect to the gate, thereby generating photoelectrons which are in the charge collection unit 26 located to the first capacitor Ca1 be transferred.

(Second switching element SW2, second capacitor Ca2)

The second switching element SW2 is formed for example by an n-channel MOS transistor, wherein the source with the charge collecting unit 26 is connected, the drain with the second capacitor Ca2 is connected and the gate is connected to a not shown gate driver circuit. Consequently, by selectively controlling ON and OFF switching of the second switching element SW2 in accordance with a gate drive signal (second readout signal sg2 ) from the gate drive circuit with respect to the gate, photoelectrons located in the charge collection unit 26 located to the second capacitor Ca2 be transferred.

Third Switching Element SW3, Charge Dispensing Unit 108

The third switching element SW3 is formed for example by an n-channel MOS transistor, wherein the source with the charge collecting unit 26 connected to the drain with the charge-discharge unit 108 is connected and a positive power source voltage Vdd from the first power supply 208A the charge-dispensing unit 108 is supplied. Further, a not shown gate driver circuit is connected to the gate. Consequently, by supplying a gate drive signal (charge-output signal Se) to the gate of the gate drive circuit, the gate is turned ON and photoelectrons located in the charge collection unit 26 be through the charge-dispensing unit 108 delivered without the first capacitor Ca1 or the second capacitor Ca2 to be transferred.

(First reset switch SR1, second reset switch SR2)

The first reset switch SR1 and the second reset switch SR2 are formed, for example, by n-channel MOS transistors. A contact point a1 between the first switching element SW1 and the first capacitor Ca1 is at the source of the first reset switch SR1 connected, and a contact point a2 between the second switching element SW2 and the second capacitor Ca2 is at the source of the second reset switch SR2 connected. A reset voltage Vr from the second power source 208B Each of the drains is supplied and an unillustrated gate driver circuit is connected to each of the gates. Thus, according to gate drive signals (first reset signal sr1 and second reset signal) from the gate drive circuit with respect to each of the gates, the first reset switch SR1 and the second reset switch SR2 selectively or simultaneously turned ON, eliminating potentials from the first capacitor Ca1 and the second capacitor Ca2 can be set to fixed reset potentials. In particular, the first capacitor Ca1 and the second capacitor Ca2 be reset.

(First amplifier AP1)

The first amplifier AP1 includes a first dispensing element TR1 which is formed, for example, by an n-channel MOS transistor, and a first output switch SEL1, which is formed for example of an n-channel MOS transistor, which is connected between a source of the first output element TR1 and a first output line 212a connected. A contact point a1 between the first switching element SW1 and the first capacitor Ca1 is at the gate of the first output element TR1 connected, a positive power source voltage Vdd from the first power source 208 the drain is supplied, and a drain of the first output switch SEL1 is connected to the source. A not shown gate driver circuit is connected to the gate, and the first output line 212a is connected to the source of the first output switch SEL1. Consequently, by turning ON the first output switch SEL1 by supplying a gate drive signal (first output selection signal ss1 ) with respect to the first output switch SEL1, a voltage corresponding to the photoelectrons (charge amount Q1 ), which in the first capacitor Ca1 stored in the first output element TR1 amplified and is queried as a first output voltage Vout1.

(Second amplifier AP2)

The second amplifier AP2 includes a second dispensing element TR2 which is formed, for example, by an n-channel MOS transistor, and a second output switch SEL2, which is formed for example of an n-channel MOS transistor, which between a source of the second output element TR2 and a second output line 212b connected. A contact point a2 between the second switching element SW2 and the second capacitor Ca2 is at the gate of the second output element TR2 connected, a positive power source voltage Vdd from the first power source 208A is supplied to the drain, and a drain of the second output switch SEL2 is connected to the source. A not shown gate driver circuit is connected to the gate and the second output line 212b is connected to the source of the second output switch SEL2. Consequently, by turning ON the second output switch SEL2 by supplying a gate drive signal (second output selection signal ss2 ) with respect to the gate of the second output switch SEL2, a voltage corresponding to the photoelectrons (charge amount Q2 ), which in the second capacitor Ca2 stored in the second output element TR2 amplified and is queried as a second output voltage Vout2.

<Operations of the second light receiving system 200B>

Next, operations of the second light receiving system 200B with reference to 20 explained. In 20 are periods during which the first to third switching elements SW1 to SW3 Are switched ON, each by WD1 to WD3 designated.

First, the controller drives 204 from the second light receiving system 200B the light-emitting device 202 at each of fixed periods (cycles) such that within a predetermined period WS, the pulsed light Lp is irradiated every one cycle for a light emission time WL. The specified period WS is a period during which luminance information is read out from ambient light Ls, and in the predetermined period WS thereof, light which is incident on the second light-receiving device 100B impinges through the photoelectric conversion element 10 converted into photoelectrons, and the photoelectrons become the charge collection unit at high speeds 26 transferred.

The first switching element SW1 transfers the photoelectrons leading to the charge collection unit 26 transferred to the first capacitor Ca1 , In particular, photoelectrons, which are to the first capacitor Ca1 be transferred, photoelectrons (charge amount Q1 ) obtained by photoelectric conversion from the incident ambient light Ls. Consequently, information regarding the intensity of ambient light can be given by the amount of charge Q1 be obtained.

After the elapse of the set period WS, pulsed light Lp (radiant light Le) emitted from the light-emitting device 202 is radiated, reflected from the object W, and is applied to the second light-receiving device 100B as reflected light Lr impinge. The light which is incident on the second light receiving device 100B is incident through the photoelectric conversion element 10 converted into photoelectrons and the photoelectrons become the charge collection unit at high speeds 26 transferred.

The second switching element SW2 transfers the photoelectrons leading to the charge collection unit 26 transferred to the second capacitor Ca2 , In particular, the photoelectrons which are to the second capacitor Ca2 were transferred, photoelectrons (charge amount Q2 ) obtained by photoelectric conversion of incident ambient light Ls and reflected light Lr (that is, reflected light consisting of pulsed light Lp reflected from the object W).

Consequently, as shown by the following equation (F1), by the difference between the amount of charge Q1 and the charge amount Q2 is taken, information can be obtained from the intensity of the reflected light which is not dependent on the ambient light. $$\text{Intensity of the reflected light}=\text{Q}1-\text{Q}2$$

In the case that the first switching element SW1 and the second switching element SW2 both are not ON (both are OFF), the photoelectrons converted by photoelectric conversion are unnecessary photoelectrons, and therefore, such unnecessary photoelectrons become the charge-dispense unit 108 delivered by the third switching element SW3 Is switched ON.

Detailed operation time settings of the second light receiving system 200B be referring to 20 explained.

Initially, similarly to the above-mentioned first light receiving system 200A Initial settings for the second light receiving system 200B performed, the third switching element SW3 , the first reset switch SR1 and the second reset switch SR2 are all turned ON and the first switching element SW1 , the second switching element SW2 , the first output switch SEL1 and the second output switch SEL2 are all turned OFF. Due to this, unnecessary photoelectrons are generated in the photoelectric conversion element 10 are stored, along with adjusting the respective potentials of the first capacitor Ca1 and the second capacitor Ca2 to the reset potential. Thereafter, the first reset switch SR1 and the second reset switch SR2 Switched off. Further, at the same time, the first voltage V1 and the second tension V2 , which is the first electrode 16a and the second electrodes 16b from the photoelectric conversion element 10 supplied with the time settings shown controlled by similar operations during the period WD3 from 20 , whereby photoelectrons, which through the photoelectric conversion element 10 be generated, which is the first electrode 16a and the second electrodes 16b encompassed by the charge delivery unit 108 are discharged, so that no charges in the photoelectric conversion element 10 remain and the photoelectric conversion element is initiated.

After the initial adjustments are completed, the cycle is performed only once, or alternatively repeated several times to obtain the intensity of the reflected light.

As in 20 is shown different from the case of the first light receiving system 200A in each of the cycles a fixed period WS from the beginning time t1 placed and as a result of that the control device 204 the light-emitting device 202 drives, a unit of pulsed light Lp from the light-emitting device 202 broadcast. Consequently, the fixed period WS serves as a time period while the ambient light Ls is being picked up.

Additionally, at the moment t1 the third switching element OFF, whereas the first switching element SW1 Is turned ON (while the second switching element SW2 and the third switching element SW3 Stay-off) of a time t1 and about the first reading period WD1 , Further, similar to the above-mentioned first light receiving system 200A from the time t1 the first tension V1 and the second tension V2 , which is the first electrode 16a and the second electrodes 16b from the photoelectric conversion element 10 be fed to high levels VH1 and VH2 set, and after that becomes at a time t2 the second tension V2 to the low level V2L set and then it will be at a time t3 the first tension V1 to the low level V1L set. According to such a serial voltage change, the photoelectrons become below the second electrodes 16b at high speeds to sites under the first electrode 16a moved, then the photoelectrons are below the first electrode 16a at high speeds to the charge collection unit 26 and then the photoelectrons become the first capacitor Ca1 through the first switching element SW1 transferred.

After that, at a time t4 the first switching element SW1 OFF, whereby together with it a unit of pulsed light Lp from the light-emitting device 202 is broadcast. Further, the second switching element SW2 ON (while the first switching element SW1 and the third switching element SW3 Stay-off) from the time t4 and over the second reading period WD2 , Further, from a time t4 the first tension V1 and the second tension V2 , which is the first electrode 16a and the second electrodes 16b from the photoelectric conversion element 10 be fed, each at high levels VH1 and VH2 set, after that will be at a time t5 the second tension V2 to the low level V2L set, and after that becomes at a time t6 the first tension V1 to the low level V1L set. According to such a serial voltage change, the photoelectrons become below the second electrodes 16b at high speeds to locations below the first electrode 16a moved, then the photoelectrons are below the first electrode 16a at high speeds to the charge collection unit 26 and then the photoelectrons become the second capacitor Ca2 through the second switching element SW2 transferred.

After that, at a time t7 the second switching element SW2 OFF, and the third switching element SW3 is turned ON (while the first switching element SW1 and the second switching element SW2 both stay off), of one period (charge-discharge period WD3 ) from the time t7 until the start of the next cycle. Accordingly, in the charge-discharge period WD3 unnecessary photoelectrons present in the photoelectric conversion element 10 are generated, via the third switching element SW3 and the charge-dispensing unit 108 issued.

In a phase following completion of a predetermined number of cycles, turning ON the first output switch SEL1 , in the first output line 212a , a voltage which the photoelectrons (charge amount Q1 ), which in the first capacitor Ca1 stored in the first output element TR1 amplifies and is output as the first output voltage Vout1. Thereafter, by turning ON the second output switch SEL2 , to the second output line 212b a voltage corresponding to the photoelectrons (charge amount Q2 ), which in the second capacitor Ca2 stored in the second output element TR2 is amplified when the second output voltage Vout2 is output.

The first output voltage Vout1 and the second output voltage Vout2 coming from the first output line 212a and the second output line 212b are output, respectively, in first numerical data D1 and second numerical data D2 is converted by an A / D converter, not shown, and the numerical data is the arithmetic processor 206 fed.

In the arithmetic processor 206 Reflected light intensity data Dr is obtained by calculating according to the following equation (F2) based on the supplied first numerical data D1 and the second numerical data D2 is carried out. $$\text{Dr = D2-D1}$$

Since the pulse width of the pulsed light Lp is longer than 1 nanosecond and shorter than 0.25 Seconds is the above-mentioned light-emitting device 202 capable of setting the pulse width of the pulsed light Lp to a length which is temporarily equal to or less than 1%, for example, equal to or less than 0.1% of a frame. In other words, due to the fact that the pulse width can be set fairly short, the energy of the one unit of pulsed light can be increased, thereby making it possible to greatly improve the S / N ratio of the reflected light component with respect to the ambient light component , The second reading period WD2 can also be set short together with the pulse width of the pulsed light Lp, while additionally the first reading period WD1 in which only ambient light Ls is read, in time to the same length as the above-mentioned second reading period WD2 can be adjusted and thus, since the reading time is made short, the amount of incident ambient light Ls can be reduced, and photon shot noise components caused by such ambient light Ls can also be reduced.

Furthermore, the time length between the first reading period WD1 and the second reading period WD2 can be made substantially zero, and therefore, switching between reading of photoelectrons during the period (first reading period WD1 ) in which pulsed light Lp is not radiated on the object (that is, detection of luminance values while no radiation takes place) and reading of photoelectrons during the period (second reading period WD2 ) while pulsed light Lp is radiated (that is, detection of luminance values during emission), in a short time, whereby simultaneity with respect to the detection of the luminance values during non-irradiation and the luminance values during irradiation is performed can be significantly improved.

Further, in the case that the above-mentioned cycle is repeated a plurality of times, the amount of photoelectrons present in the first capacitor Ca1 and the second capacitor Ca2 stored are increased. Also in this case, due to the fact that the duty ratio of pulsed light Lp with respect to the pulse period of the series of pulsed light is set to 1% or less (for example, 0.1% or less), the energy of each of the units of pulsed light Lp contained within the series of pulsed light are made higher than that of continuous light, and the S / N ratio of reflected light Lr (signal light component) to ambient light (perturbation component) in each pulse width can be significantly improved. In this way, by making the duty ratio of the pulsed light Lp small, even if pulsed light having a large output power is used because heat can be emitted while an emission of light rests, an advantageous heat dissipation characteristic is enabled. In addition, due to the fact that photoelectrons in each case in the first capacitor Ca1 and the second capacitor Ca2 are stored over a plurality of cycles, the signal light component is increased, and the accuracy of subsequent signal processing thereof can be improved. Further, because within each cycle, switching between reading of photoelectrons in the first reading period WD1 and reading photoelectrons in the second reading period WD2 can be performed in a short time, simultaneity with respect to detection of luminance values during non-irradiation and luminance values during irradiation can be significantly improved.

[First Distance Measuring Device 300A]

Next, a distance measuring device (hereinafter referred to as a first distance measuring device 300A referred to) according to a first embodiment with reference to the 21 to 26 to be discribed.

The first distance measuring device 300A serves to obtain a three-dimensional image in which a measured distance is used based on outputs from respective pixels 304 from an image sensor described later 302 , and includes a third light receiving device 100C in addition to the above-mentioned light-emitting device 202 , the controller 204 , the arithmetic processor 206 , the first energy source 208A , and the second energy source 208B ,

With the first distance measuring device 300A is pulsed light Lp, which comes from a light emitter 210 from the light-emitting device 202 in response to a command from the controller 204 is radiated, reflected by an object W, and brought to the third light-receiving device 100C impinge. Ambient light Ls of sunlight or the like also hits the third light receiving device 100C on. The third light receiving device 100C gives a signal to the arithmetic processor 206 indicative of a charge corresponding to a received amount of light based on a command from the controller 204 , The arithmetic processor 206 calculates a time period (orbital period .DELTA.P) [s] which requires the pulsed light Lp to be emitted from the light-emitting device 202 at the third light receiving device 100C to arrive and based on the Umlaufzeitperiode .DELTA.P it calculates a distance D [m] between the first distance measuring device 300A and the object. The calculation result from the arithmetic processor 206 is output to a display device, not shown.

<Third Light Receiving Device 100C>

The third light receiving device 100C includes a lens 102 and a third light receiving unit 104C , Reflected light Lr passing through the lens 102 happens, and ambient light Ls, be on the third light receiving unit 104C focused. The Lens 102 may also comprise a plurality of lenses arranged in a row or in a matrix.

As in 22 shown comprises the third light receiving unit 104C an image sensor 302 in which pixel 304 are arranged in a matrix form, a gate driver circuit 306 , a vertical selection circuit 308 a sample and hold circuit 310 , a horizontal selection circuit 312 , an output buffer 314 and an A / D converter 316.

The image sensor 302 gives via the horizontal selection circuit 312 accumulated charge signals Sc1 . sc2 which correspond to the amount of light coming from each of the pixels 304 Will be received. The first source of energy 208A sets a positive power source voltage Vdd with respect to the image sensor 302 on, and the second energy source 208B sets a reset voltage Vr with respect to the image sensor 302 at.

The gate driver circuit 306 controls ON / OFF states from the first to fifth switching elements SW1 to SW5 (please refer 23 ) and from the first to fourth reset switches SR1 to SR4 from the image sensor 302 by outputting different types of gate drive signals.

The vertical selection circuit 308 comprises a multiplexer (not shown) which selectively outputs first through fourth output select signals ss1 to Ss4 outputs with respect to rows to which pixels to be read 204 belong, and also accumulated charge signals Sc1 . sc2 from the pixels 304 outputs. The horizontal selection circuit 312 comprises another multiplexer (not shown) for selecting columns to which pixels to be read ( 304 ) belong.

As in 23 shown, the accumulated charge signals Sc1 . sc2 which of the pixels 304 are read out into first and second output voltages Vout1, Vout2 by a first fixed current circuit 58a and in third and fourth output voltages Vout 3 , Vout4 through a second fixed current circuit 58b once converted to the sample and hold circuit 310 they are collected by the horizontal selector circuit 312 output. In addition, the accumulated charge signals Sc1 . sc2 to the arithmetic processor 206 through the output buffer 314 and the A / D converter 316. The arithmetic processor 306 , which the accumulated charge signals Sc1 . sc2 has received, determines a light amount (light amount Ar) of the reflected light Lr from the accumulated charge signals Sc1 . sc2 and calculates the distance D between the first distance measuring device 300A and the object W (to be described later in detail).

<Pixel 304>

In 23 is a circuit diagram of one pixel 304 shown. As in 23 shown is the pixel 304 with the above-mentioned photoelectric conversion element 10 , the cargo collection unit 26 , first to fourth capacitors Ca1 to Ca4 , the charge delivery unit 108 , and first to fifth switching elements SW1 to SW5 and further includes first to fourth reset switches SR1 to SR4 and first to fourth amplifiers AP1 to AP4 , To make the circuit diagram easier to see, the charge collection unit is 26 in 23 shown by two contact points, but in reality the points of contact are common in a charge collection unit 26 educated. Further, the first capacitor Ca1 and the third capacitor Ca3 at symmetrical positions with respect to the center of the charge collection unit 26 arranged, and the second capacitor Ca2 and the fourth capacitor Ca4 are also at symmetrical positions with respect to the center of the cargo collection unit 26 arranged. Similarly, the first capacitor Ca1 and the second capacitor Ca2 at symmetrical positions with respect to the center of the charge collection unit 26 arranged, and the third capacitor Ca3 and the fourth capacitor Ca4 are also at symmetrical positions with respect to the center of the cargo collection unit 26 arranged.

(First switching element SW1, first capacitor Ca1)

The first switching element SW1 and the first capacitor Ca1 have the same structure as that of the above-mentioned second light receiving device 100B and therefore explanations of these features are omitted.

(Second switching element, second capacitor)

The second switching element SW2 and the second capacitor Ca2 have the same structure as that of the second mentioned above Light receiving means 100B and therefore, explanations of these features are omitted.

(Third switching element SW3, third capacitor Ca3)

The third switching element is formed, for example, by an n-channel MOS transistor, wherein the source with the charge collecting unit 26 connected, the drain with the third capacitor Ca3 is connected and the gate with the gate driver circuit 306 connected is. Consequently, ON and OFF states of the third switching element SW3 selectively according to a gate drive signal (third readout signal Sg3 ) from the gate driver circuit 306 controlled with respect to the gate, whereby photoelectrons, which are in the charge collecting unit 26 located, to the third capacitor Ca3 be transferred.

(Fourth switching element SW4, fourth capacitor Ca4)

The fourth switching element SW4 is formed for example by an n-channel MOS transistor, wherein the source with the charge collecting unit 26 connected, the drain to the fourth capacitor C1 is connected and the gate with the gate driver circuit 306 connected is. As a result, ON and OFF states of the fourth switching element SW4 selectively according to a gate drive signal (fourth readout signal sg4 ) from the gate driver circuit 306 controlled with respect to the gate, whereby photoelectrons, which are in the charge collecting unit 26 to the fourth capacitor Ca4 be transferred.

(Fifth Switching Element SW5, Charge Dispensing Unit 108)

The fifth switching element SW5 is formed for example by an n-channel MOS transistor, wherein the charge collecting unit 26 connected to the source, the charge-dispense unit 108 is connected to the drain, and a positive power source voltage Vdd from the first power source 208A the charge-dispensing unit 108 is supplied. Further, a charge-output signal Se becomes the gate of the gate drive circuit 306 fed.

Consequently, by supplying the charge-output signal Se to the gate (that is, by setting the voltage supplied to the gate to a high level), the gate is turned ON and unnecessary photoelectrons appearing in the charge collection unit 26 be through the charge-dispensing unit 108 delivered without the first to fourth capacitors Ca1 to Ca4 to be transferred.

In particular, when all of the first to fourth switching elements SW1 to SW4 OFF, that is, when the photoelectrons passing through the photoelectric conversion element 10 are generated, not the first to fourth capacitors Ca1 to Ca4 is assigned) by transmission of the charge-output signal Se from the gate drive circuit 306 to the fifth switching element SW5 (That is, by setting the voltage supplied to the gate to a high level) the fifth switching element SW5 ON and unnecessary photoelectrons emitted from the photoelectric conversion element 10 can be generated by the charge-dispensing unit 108 are discharged without the first to fourth capacitors Ca1 to Ca4 to be assigned. Due to this, it becomes possible for only photoelectrons to be emitted from the photoelectric conversion element 10 are generated while periods are assigned when the first to fourth switching elements SW1 to SW4 Are ON. As a result, by a later-described method, the distance D between the first distance measuring device 300A and the object W are measured.

(First to fourth reset switches SR1 to SR4)

The first to fourth reset switches SR1 to SR4 are formed, for example, by n-channel MOS transistors. A contact point a1 between the first switching element SW1 and the first capacitor Ca1 is at the source of the first reset switch SR1 connected, and a contact point a2 between the second switching element SW2 and the second capacitor Ca2 is at the source of the second reset switch SR2 connected. Similarly, a contact point a3 between the third switching element SW3 and the third capacitor Ca3 with the source from the third reset switch SR3 connected, and a contact point a4 between the fourth switching element SW4 and the fourth capacitor Ca4 is at the source of the fourth reset switch SR4 connected. A reset voltage Vr from the second power supply 208B is supplied to each of the drains and the gate driver circuit 306 is connected to each of the gates.

Consequently, the gate drive signals (first to fourth reset signals sr1 to sr4 ), which of the gate driver circuit 306 with respect to each of the gates, the first to fourth reset switches SR1 to SR4 selectively or simultaneously turned ON, eliminating potentials from the first to fourth capacitors Ca1 to Ca4 can each be set to fixed reset potentials. In other words, the first to fourth capacitors Ca1 to Ca4 be reset.

(First amplifier AP1, second amplifier AP2)

The first amplifier AP1 and the second amplifier AP2 have the same structure as those of the first amplifier AP1 and the second amplifier AP2 from the second light receiving device described above 100B and therefore detailed descriptions thereof will be omitted. However, the source of the first output switch SEL1 is from the first amplifier AP1 with the first output line 212a connected, and the first output selection signal ss1 is the gate thereof from the vertical selection circuit 308 fed. Similarly, the source is from the second output switch SEL2 from the second amplifier AP2 with the first output line 212a connected and the second output selection signal ss2 is the gate thereof from the vertical selection circuit 308 fed.

Consequently, by turning ON the first output switch SEL1 in accordance with the first output selection signal ss1 , which is supplied with respect to the gate of the first output switch SEL1, a voltage which the photoelectrons (charge amount Q1 ), which in the first capacitor Ca1 stored in the first output element TR1 amplified, and is referred to as a first output voltage Vout1 via the first output line 212a taken. Similarly, turning ON the second output switch will turn ON SEL2 in accordance with the second output selection signal ss2 which is relative to the gate of the second output switch SEL2 is supplied, a voltage which the photoelectrons (charge amount Q2 ), which in the second capacitor Ca2 stored in the second output element TR2 amplifies and is referred to as a second output voltage Vout2 via the second output line 212a taken.

(Third amplifier AP3)

The third amplifier AP3 includes a third output element TR3 which is formed, for example, by an n-channel MOS transistor, and a third output switch SEL3, which is formed for example of an n-channel MOS transistor, which between a source of the third output element TR3 and the second output line 212b connected. A contact point a3 between the third switching element SW3 and the third capacitor Ca3 is at the gate of the third output element TR3 connected, a positive power source voltage Vdd from the first power source 208A the drain is supplied, and a drain of the third output switch SEL3 is connected to the source. The third output switch SEL3 is arranged such that the second output line 212b connected to the source, and a first output selection signal ss3 from the vertical selection circuit 308 is supplied to the gate.

Consequently, by turning ON the third output switch SEL3 in accordance with the third output selection signal ss3 , which is supplied with respect to the gate of the third output switch SEL3, a voltage which the photoelectrons (charge amount Q3 ), which in the third capacitor Ca3 stored in the third output element TR3 amplifies and is as a third output voltage Vout3 via the second output line 212B taken.

(Fourth amplifier AP4)

The fourth amplifier AP4 includes a fourth output element TR4 which is formed, for example, by an n-channel MOS transistor, and a fourth output switch SEL4, which is formed for example of an n-channel MOS transistor, which is connected between a source of the fourth output element TR4 and the second output line 212b connected. A contact point a4 between the fourth switching element SW4 and the fourth capacitor Ca4 is at the gate of the fourth output element TR4 connected, a positive power source voltage Vdd from the first power source 208a the drain is supplied, and a drain of the fourth output switch SEL4 is connected to the source. The fourth output switch SEL4 is arranged such that the second output line SEL4 212b connected to the source, and a fourth output selection signal Ss4 from the vertical selection circuit 308 is supplied to the gate.

Consequently, by turning ON the fourth output switch SEL4 in accordance with the fourth output selection signal Ss4 , which is supplied with respect to the gate from the fourth output switch SEL4, a voltage corresponding to the photoelectrons (charge amount Q4 ), which in the fourth capacitor Ca4 stored in the fourth output element TR4 amplifies and is referred to as a fourth output voltage Vout4 via the second output line 212b taken.

Method for measuring a distance D between a first distance measuring device 300A and an object W

Next, a method for measuring the distance D between the first distance measuring device 300A and the object W are explained.

Cycle Cm

As in 24 is shown in the first distance measuring device 300A every cycle (one Period in which a measured value is determined) [times / second] from a first collection period Tca1 during charges in the first to fourth capacitors Ca1 to Ca4 are accumulated cumulatively, and a readout period Tr during which the charges are read out, cumulatively in the first to fourth capacitors Ca1 to Ca4 were saved. Further, in the first collection period Tca1, a plurality of second collection periods Tca2 are included, during which the pixels 304 are subjected to pulsed light, and processing (charge accumulation processing) is performed once to charge in the first to fourth capacitors Ca1 to Ca4 to accumulate. In the first distance measuring device 300A the first collection period is Tca1 and the readout period Tr1 ten milliseconds. Further, each of the second collection periods Tca2 is 100 microseconds. Further, the readout time (pulse width) of pulsed light Lp in each of the second collection periods Tca2 is 100 nanoseconds. Consequently, the duty cycle with which the light emitter is 210 0.1% in each of the second collection periods Tca2.

As noted above, since the first distance measuring device 300A is capable of outputting the measurement result as a three-dimensional image, each of the cycles Cm may be defined as a frame rate [frames / second / frame / second] of the three-dimensional image.

In the first distance measuring device 300A becomes a cargo collection processing 100 Times in the first collection period Tca1, and together with them, the round trip period ΔP and the distance D based on the charges Q1 to Q4 measured in the first to fourth capacitors Ca1 to Ca4 are stored.

(2) Outline of the measurement procedure (for one charge collection period TCA2 ) Although in the foregoing manner with the first distance measuring device 300A the round trip period .DELTA.P and the distance D based on the charges Q1 to Q4 which are measured in the first to fourth capacitors Ca1 to Ca4 over the entirety of the first collection period TCA1 In order to facilitate the understanding of the invention, an explanation will first be made below in a case where the round trip period .DELTA.P and the distance D based on the charges Q1 to Q4 which are determined in the first to fourth capacitors Ca1 to Ca4 over only one of the second collection periods TCA2 get saved.

In 25 Fig. 12 is a timing chart for irradiation light Le and reflected light Lr shown together with ON / OFF states of the first to fifth switching elements SW1 to SW5 ,

Although details of this are to be described later, the first distance measuring device is used 300A Assuming that the intensity Ir [W] of the reflected light Lr is constant, the distance D measured using a proportional relationship between the period (reflected light incident time period Pri) [s], while the reflected light Lr on the photoelectric conversion element 10 and the cumulative light amount (measured light reflected amount Amr) [J] of the reflected light Lr in the reflected light incident time period Pri.

In particular, in a period of time P1 as a first standard period, a cumulative light amount (standard ambient light amount Ars) [J] (charge amount Q1 from the first capacitor Ca1 ) at a time when only ambient light Ls is applied to the photoelectric conversion element 10 is incident, determined and in a time period P3 (= P1) as a second standard period, a cumulative light amount (standard composite light amount Ari) [J] (charge amount Q3 from the third capacitor Ca3 ) at a time when ambient light Ls and reflected light Lr both on the photoelectric conversion element 10 hit, determined. Further, in a period of time P2 as a first measurement period, a cumulative amount of light (measured ambient light amount Ams) [J] (charge amount Q2 from the second capacitor Ca2 ) at a time when only ambient light Ls is applied to the photoelectric conversion element 10 hits, determines, and in a time period P4 (= P2 ) as a second measurement period, a cumulative amount of light (measured-composite light amount Ami) [J] (charge amount Q4 from the fourth capacitor Ca4 ) at a time when both ambient light Ls and reflected light Lr are applied to the photoelectric conversion element 10 hit, determined. A period (time period Psr) [s] in which both ambient light Ls and reflected light Lr are incident, and a period (time period Ps) [s] in which only ambient light Ls are incident are in the time period P4 available. The time period Psr is proportional to the distance D to the object W.

The ratio (Ari-Ars: Ami-Ams) of the difference (standard reflected light amount Arr) [J] between the standard composite light amount Ari and the standard ambient light amount Ars and the difference (measured-reflected Light Amr) [J] between the measured composite light Ami and the measured Ambient Ams is equal to the ratio ( P3 : Pri) from the time period P3 (= P1) and the reflected light incident time period Pri. Using this fact, the time period (orbital period ΔP) over which pulsed light Lp emitted by the first distance measuring device becomes 300A is broadcast on the object W hits and until the pulsed light Lp to the first distance measuring device 300A returns, determined. Based on the period of revolution ΔP, the distance becomes D between the first distance measuring device 300A and the object W measured.

Details of the measurement method (for a one-second collection period Tca2)

Description of the timing diagram

In 25 T e denotes a radiation start time of a radiation light time Le, Ted denotes a radiation end time of the radiation light Le, and the time period Pe denotes a time period from the time Teu to the time Ted. A time Tru denotes an incident start time of reflected light Lr with respect to the photoelectric conversion element 10 , a time Trd denotes an incident end time of the reflected light Lr with respect to the photoelectric conversion element 10 and a time period Pr denotes a time period from the time Tru to the time Trd.

times Tg1u . Tg2u . Tg3u . Tg4u designate times at which the first to fourth switching elements SW1 to SW4 Be turned ON, times Tg1d . Tg2d . Tg3d . Tg4d thereafter, times designate the first to fourth switching elements SW1 to SW4 OFF, a period of time P1 denotes a period of time Tg1u by the time Tg1d , a period of time P2 denotes a period of time Tg2u by the time Tg2d , a period of time P3 denotes a period of time Tg3u by the time Tg3d , and a period of time P4 denotes a period of time Tg4u by the time Tg4d , A time period Psr denotes a time period of time Tg4u at the time Trd, and a period of time Ps denotes a period of time from the time Trd to the time Tg4d ,

times Td1u . Td2u denote times to which the fifth switching element SW5 ON, times Td1d . Td2d denote times to which the fifth switching element SW5 OFF, a period of time P5 denotes a period of time Td1u by the time Td1d and a time period P6 denotes a period of time Td2u by the time Td2d ,

During a period of time Pr, while the reflected light on the photoelectric conversion element 10 a delay generated (round trip time period ΔP) from a time Teu to a time Tru or from a time Ted to a time Trd) corresponds to a time period Pr of a time period Pe (Pe = Pr) and can be, for example, between 10 nanoseconds or more and 1 Microseconds or less, and in the first distance measuring device 300A it is set to 100 nanoseconds. Further, in the control device 204 a period of time P1 and a time period P3 as well as a period of time P2 and a time period P4 set so that they each correspond to each other ( P1 = P3 and P2 = P4 ). For example, time periods P1 and P3 be set between 10 nanoseconds and more and 90 nanoseconds or less and in the first distance measuring device 300A they are set to 30 nanoseconds. A period of time P2 For example, it may be set between 10 nanoseconds or greater and 90 nanoseconds or less, and in the first distance measuring device 300A it is set to 70 nanoseconds. Furthermore, a period of time P5 for example, between 0 nanoseconds or more and 90 nanoseconds or less, and in the first distance measuring device 300A it is set to 70 nanoseconds. A period of time P6 For example, it may be set between 10 nanoseconds or more and 1 millisecond or less, and in the first distance measuring device 300A it is set to 100 microseconds. Hence the time period P6 under the time periods P1 to P6 very long.

How out 25 is understandable, in the second collection period Tca2 from the first distance measuring device 300A First, the first switching element SW1 ON-switched (time period P1 ) and simultaneously with the turn-OFF of the first switching element SW1 becomes the second switching element SW2 ON-switched (time period P2 ). Then, simultaneously with the turn-OFF of the second switching element SW2 Radiation light Le with respect to the object W emitted and the fifth switching element SW5 is switched ON (time period P5 ). During an emission of radiation light Le (time period Pe), an incident of reflected light Lr with respect to the photoelectric conversion element becomes 10 started (currently Tru). After the passage of the time period P5 from the irradiation start time of the irradiation light Le (time Teu) becomes the fifth switching element SW5 OFF and together with it becomes the third switching element SW3 ON-switched (time period P3 ). Then, after the passage of the time period Pe, emission of the radiation light Le is stopped, and together with this becomes the third switching element SW3 OFF and the fourth switching element SW4 is switched ON (time period P4 ). At a time during which the fourth switching element SW4 Is ON (time period P4 ) becomes an incident of reflected light with respect to the photoelectric conversion element 10 stopped (time Trd). In other words, the time period defines P4 the measuring range (range of distances for which a measurement is possible) [m] from the first distance measuring device 300A , Simultaneously with the turn OFF of the fourth switching element SW4 becomes the fifth switching element SW5 Switched on ( time period P6 ). On the passage of the time period P6 towards the fifth switching element SW5 OFF and one cycle of the second collection period Tca2 comes to an end (time Td2d ). Simultaneously with this, a next second collection period Tca2 is started and the first switching element SW1 turns ON (time Tg1u ). Controls / arrangements for both the third receiving device 110C as well as the light-emitting device 202 be in the controller 204 carried out. In the case that the control device 204 is prepared by a semiconductor process, it is further preferable from the viewpoint of temperature compensation, etc., that the controller 204 together with the third light receiving unit 104C on the same silicon substrate by a CMOS process.

Description of measuring principles

Calculation of a standard reflected light amount Arr

Assuming that the first distance measuring device 300A and the object W are fixed in respective positions, reflected light Lr which is reflected by the object W and the first distance measuring device 300A returns, the target value of a constant intensity (amount of light per unit time) to be. Further, since the time period P1 is set to a period of time while only the ambient light Ls is applied to the photoelectric conversion element 10 incident, photoelectrons are due to the ambient light Ls only in the first capacitor Ca1 saved. On the other hand, there is a time period P3 is set to a time period during which both the ambient light Ls and the reflected light Lr are applied to the photoelectric conversion element 10 are incident photoelectrons by both ambient light Ls and reflected light Lr in the third capacitor Ca3 saved. In addition, have the time period P1 and the time period P3 the same length.

Due to this, the difference between the charge amount leaves Q3 which is in the third capacitor Ca3 is stored, and the amount of charge Q1 which is in the first capacitor Ca1 is stored at an accumulated light amount (standard reflected light amount Arr) of reflected light Lr in the time period P3 (= Time period P1 ).

Calculating a measured-reflected light amount Amr and a round-trip period ΔP

Assuming that the first distance measuring device 300A and the object W are fixed in respective positions, reflected light Lr which is reflected by the object W and the first distance measuring device 300A returns, the target value of a constant intensity. Further, there is a period of time P2 is set to a time period while only the ambient light Ls is applied to the photoelectric conversion element 10 incident, photoelectrons due to ambient light Ls only in the second capacitor Ca2 saved. On the other hand, since the time period P4 is set to a time period including a period of time Psr during which both the ambient light Ls and the reflected light Lr are applied to the photoelectric conversion element 10 while the only ambient light Ls is incident on the photoelectric conversion element 10 incident to photoelectrons by both ambient light Ls and reflected light Lr in the fourth capacitor Ca4 saved. In addition, have the time period P2 and the time period P4 the same length.

Due to this, the difference between the amount of charge can be understood Q4 which is in the second capacitor Ca4 is stored, and the amount of charge Q2 which is in the second capacitor Ca2 is stored close to an accumulated light amount (measured-reflected light amount Amr) of reflected light Lr in the time period P4 (= Time period P2 ). In the first distance measuring device 300A becomes a period of time P4 started simultaneously with the time Ted, at which an irradiation of the radiation light Le is stopped. As a result, during the period of time P4 reflected light Lr corresponding to the pulse rotation ΔP to the photoelectric conversion element 10 be incident and photoelectrons become in the fourth capacitor C4 saved. Consequently, the charge amount corresponds Q4 which is in the fourth capacitor Ca4 is the sum (measured-composite light amount Ami) of the accumulated light amount of ambient light Ls (measured ambient light Ams) and the collected light amount of reflected light Lr (measured-reflected light Amr) over the entire time period P4 , Due to this, the difference between the charge amount leaves Q4 and the charge amount Q2 to a charge amount corresponding to the measured-reflected light amount Amr. The round trip period ΔP depends on the distance D between the first distance measuring device 300A and the object W. Therefore, the ratio between the measured-reflected light amount Amr (which is the difference between the amount of charge Q4 and the charge amount Q2 corresponds to) and the standard reflected light amount Arr, (which is the difference between the amount of charge Q3 and the charge amount Q1 corresponds) equal to the ratio between the round trip period .DELTA.P and the time period P3 (= time period P1) (Amr: Arr = Q4-Q2: Q3-Q1 = ΔP: P3). Thus, the round trip period ΔP can be calculated by the following equation (F3). $$\Delta \text{P =}\left\{\left(\text{Q}4-\text{Q}2\right)/\left(\text{Q}3-\text{Q}1\right)\right\}\times \text{P3}$$

Calculation of the distance D

If the round trip time period ΔP is known, the distance D between the first distance measuring device 300A and the object W are calculated by the following equation (F4). In equation F4, c is a constant that indicates the speed of light (about 300,000 km per second). Further, the reason that the product c × ΔP is divided by two is the fact that the gap between the first distance measuring device 300A and the object W is traversed back and forth by the pulsed light Lp in the round trip time period ΔP, thus obtaining a distance which is twice the distance D is. $$\text{D =}\left(\text{c}\times \mathrm{\Delta }\text{P}\right)/2$$

(iv) Other features

As initial settings (reset operations) for the pixel 304 For example, processes such as those described below may be performed. Specifically, first, the first to fourth reset switches SR1 to SR4 simultaneously ON according to transmission from the first to fourth reset signals sr1 to sr4 in terms of the first to fourth reset switches SR1 to SR4 ( d .H. the voltages corresponding to the respective gates of the first to fourth reset switches SR1 to SR4 be fed are set to a high level). At the same time, the fifth switching element SW5 ON-switched by transmission of the charge-output signal Sde to the fifth switching element SW5 ( d .H. the voltage which is the fifth switching element SW5 is fed, is set to a high level). At this time, by a control of the fifth switching element SW5 and the first tension V1 and the second voltage V2 , which is the first electrode 16a and the second electrodes 16b from the photoelectric conversion element 10 are fed using the same timing and operations which in the above time period WD3 from 20 are shown, photoelectrons, which from the photoelectric conversion element 10 which are the first electrode 16a and the second electrodes 16b includes, via the charge delivery unit 108 are discharged so that charges do not exist in the photoelectric conversion element 10 remain, causing the photoelectric conversion element 10 is initialized (it should be noted, however, that SW3 in 20 SW5 in the pixel 304 corresponds).

Further, gate drive signals sg1 to sg4 with respect to the first to fourth switching elements SW1 to SW4 not sent ( d .H. the voltages corresponding to the respective gates of the first to fourth switching elements SW1 to SW4 supplied) are brought to a low level), whereby the first to fourth switching elements SW1 to SW4 Turned off. As a result of this process, the first to fourth capacitors Ca1 to Ca4 set to the reset potential. Then, after transmission from the first to fourth reset signals SR1 to SR4 in terms of the first to fourth reset switches SR1 to SR4 stopped ( d .H. the voltages corresponding to the respective gates of the first to fourth reset switches SR1 to SR4 supplied are set to a low level), the above-mentioned processes with the in 25 shown time settings performed.

Details of the measurement procedure (for a first collection period Tca1)

In the sections above ( 2 ) and (3) a case has been described for a second collection period Tca2. However, with the first distance measuring device 300A the round trip period ΔP is calculated in the same manner as described above using charges Q1 to Q4 which are in the first to fourth capacitors Ca1 to Ca4 are stored (hereinafter referred to as "charge amounts sq1 to sQ4 "), but by using more than 100 events from the second collection period Tca2 ( d .H. in the first collection period TCA1 ).

The charge amount sq1 is the total amount of the charge amounts Q1 which are in the first capacitor Ca1 in each case 1 st to 100 th events are stored by the second collection period Tca2. Similarly, the charge amounts sq2 to sq4 the total amounts of the charges Q2 to Q4 , which in the second to fourth capacitors Ca1 to Ca4 are stored over respective 1st to 100th processes of the second collection period Tca2.

In this case, the round trip period ΔP can be calculated by the following equation (F5) according to the foregoing equation (F3). $$\mathrm{\Delta }\text{P =}\left\{\left(\text{sQ}4-\text{sQ}2\right)/\left(\text{sQ}3-\text{sQ}1\right)\right\}\times \text{P3}$$

Based on the round trip period .DELTA.P , which is determined by the equation F5, can the distance D between the first distance measuring device 300A and the object W are determined using the foregoing equation (F4). Solutions for such calculations can be found in the arithmetic processor 206 be determined.

In this way, if the distance is due to the charge amounts sq1 to sq4 what is determined in the first to fourth capacitors Ca1 to Ca4 are stored in one hundred operations from the second collection period Tca2, the signal light component may be amplified, and thereafter, signal processing accuracy (distance calculation accuracy) may be increased.

Other characteristics

With the first distance measuring device 300A becomes the distance D using amounts of charge Q1 to Q4 (Charge information) in a plurality of respective pixels 304 measured. As a result, a three-dimensional image can be obtained by the distance information in each of the pixels 304 be combined with each other.

[Effects of the First Distance Measuring Device 300A]

With the first distance measuring device described above 300A the dynamic range of the distance measurement can be improved and the influence of ambient light Ls can be reduced or eliminated.

In particular, in the first distance measuring device 300A a charge amount Q1 which in a period of time P1 is accumulated while the only ambient light Ls on the photoelectric conversion element 10 impinges, and a charge amount Q3 which in a period of time P3 is accumulated while the both ambient light Ls and reflected light Lr on the photoelectric conversion element 10 hit, determined. By time periods P1 and P3 can be set to the same length, a charge amount, which reflected light Lr in the period of time P3 corresponds to d .H. the standard reflected light amount Arr of reflected light Lr in the time period P3 ) from the difference between the amount of charge Q3 and the charge amount Q1 ( Q3 - Q1 ).

Further, a charge amount Q2 which in a period of time P2 is accumulated while the only ambient light Ls on the photoelectric conversion element 10 impinges, and a charge amount Q4 which in a period of time P4 accumulated, determined. In the period of time P4 are a period (time period Psr) during which both the ambient light Ls and the reflected light Lr are applied to the photoelectric conversion element 50 and one period (time period Ps) while only the ambient light is applied to the photoelectric conversion element 50 impinges, included. Due to the fact that the time period P2 and the time period P4 are set to the same length, a charge amount corresponding to the time period Psr within the time period can be set P4 corresponds (which corresponds to the reflected light Lr in the period of time Psr) from the difference between the charge amount Q4 and the charge amount Q2 be determined ( Q4 - Q2 ).

When the interval during the reflected light on the photoelectric conversion element 10 is incident, and the intensity Ir of the reflected light Lr is constant, then the ratio of the difference between the charge amounts Q4 and Q2 and the difference between the amounts of charge Q3 and Q1 (Q4 - Q2: Q3 - Q1) equal to the ratio of the time period Psr and the time period P3 (Psr: P3 ). Due to this, the time period Psr can be determined by the following equation (F6). $$\text{Psr =}\left\{\left(\text{Q}4-\text{Q}2\right)/\left(\text{Q}3-\text{Q}1\right)\right\}\times \text{P3}$$

Because time is Ted and time Tg4u are equal, the period of time Psr is equal to the round trip time period .DELTA.P , Consequently, the round trip period .DELTA.P can be calculated from the equation (F6) above and as a result the distance D based on the orbital period ΔP and the speed of light.

In this way, with the first distance measuring device 300A because of the charge amount Q2 , which occurs due to ambient light Ls, can be removed, the influence of ambient light Ls eliminated or reduced.

Further, while the distance D becomes shorter, the incident period of the reflected light (ie, the time period Psr) becomes shorter, whereas when the distance D becomes longer, the period of time Psr becomes longer. In general, if the same object W is used, the distance will be during the D becomes shorter, the intensity Ir of the reflected light Lr larger, whereas, when the distance D becomes longer, the intensity Ir of the reflected light Lr becomes smaller. Therefore, in the case of a short distance D reflected light Lr, which has a large intensity Ir, for a short period of time, while in the case of a long distance D , reflected light Lr having a small intensity Ir is allowed to be incident for a long period of time. As a result, the distance is compared with the amount of change D the amount of change in the light amount Ar of reflected light Lr incident in the period of time Psr, small. Such a practice leads to an improvement in the dynamic range of the first distance measuring device 300A ,

With the first distance measuring device 300A In each cycle Cm pulsed light Lp is emitted one hundred times, and after the photoelectrons each hundred times in the first to fourth capacitors Ca1 to Ca4 is collected, the circulation time amount ΔP is calculated by using the charge amounts Q1 to Q4 calculated. In general, the intensity of ambient light Ls (eg sunlight) is constantly changing. By emitting the pulsed light Lp one hundred times in each cycle Cm, and the round trip period .DELTA.P using amounts of charge Q1 to Q4 is calculated, after the photoelectrons have been collected one hundred times accordingly, the intensity of the ambient light Ls can be averaged. As a result, the precision in removing charge amounts occurring due to ambient light Ls can be improved, and measurement accuracy can be increased.

With the first distance measuring device 300A For example, the pulse width (output time period) of the pulsed light Lp is 10 microseconds (= 100 nanometers x 100 times), which is 0.05% of each cycle Cm (20 milliseconds). Related to this are time periods P1 to P4 during which the first to fourth switching elements SW1 to SW2 ON, adjusted so that they are shorter. For this reason, even in the case where another distance measuring device using pulsed light of the same frequency is in the vicinity of the first distance measuring device 300A is low, the possibility that the time setting at which the other distance measuring device outputs pulsed light will interfere with the timing at which the first distance measuring device 300A pulsed light Lp outputs. As a result, the possibility of interference with another distance measuring device (ie, the pulsed light from the other distance measuring device may erroneously be considered as pulsed light Lp from the first distance measuring device 300A is detected) can be reduced.

In addition, since the time periods P1 to P4 during which the first to fourth switching elements SW1 to SW4 Are ON, also set so that they are short, the time period, while the ambient light Ls in the time periods P1 to P4 on the photoelectric conversion element 10 hits, be made short. This makes it possible to make the influence of ambient light Ls as a perturbation component small, and improves the signal-to-noise (S / N) ratio. Especially in the case that ambient light Ls is sunlight, shot noise of sunlight may be reduced.

With the first distance measuring device 300A are time periods P1 to P4 during which the first to third switching elements SW1 to SW4 in each cycle Cm are ON, extremely short. For this reason, the possibility that a phenomenon (so-called "aliasing") occurs in which pulsed light Lp radiated in the earliest last cycle Cm is detected in the current cycle Cm can be reduced. In particular, since each of the collection periods TCA2 from the first distance measuring device 300A 100 Microseconds and the period of time Pe during which the pulsed light Lp is emitted is short, such pulsed light Lp is emitted at intervals of about 100 microseconds. Since the speed of light c is about 300,000 kilometers per second, the possibility of aliasing exists only if the current position of the object W is fifteen kilometers (= 100 μs × 30 [Mm / s] / 2) farther than the distance D is which of the first distance measuring device 300A is issued. However, since the intensity of pulsed light Lp which is related to the object W from the light emitter 210 is broadcast, proportional to the square of the distance D is reduced, the intensity Ir of reflected light Lr is from a position fifteen kilometers farther away than the distance D , compared with the intensity Ir of reflected light Lr from the object W in the distance D very small, which makes it almost impossible for the photoelectric conversion element 10 makes to detect such reflected light Lr. Consequently, the first distance measuring device 300A prevent the occurrence of aliasing.

[Other timing diagrams]

In the examples given above, the first to fourth switching elements become SW1 to SW4 according to the time diagram of 25 controlled, but the invention is not limited to this feature. For example, the time periods P3 . P4 from 25 before the time periods P2 . P1 be positioned. Further, find the time Tg1d and the time Tg2u at the same time, however, time may Tg2u also later than or after the time Tg1d occur. The relationship between time Tg2d and time Teu is also the same as the relationship between time Tg3d and time Tg4u , Further, the time has to be Tg4u not necessarily take place at the same time as the time Ted, as long as a correlative relationship between time Tg4u and time Ted is known.

In 26 a timing diagram is shown in which the time Ted after the time tg4 occurs. In this case, the round trip period ΔP may be lower than Using the following equation (F7). $$\mathrm{\Delta }\text{P}=\left[\left(\text{Q}4-\text{Q}2\right)/\left(\text{Q}3-\text{Q}1\right)\right]\times \text{P3}\left(\text{Ted Tg4u}\right)$$

Alternatively, the time Ted ahead of time Tg4u occur. In this case, the round trip period ΔP can be calculated using the following equation (F8). $$\mathrm{\Delta }\text{P}=\left[\left(\text{Q}4-\text{Q}2\right)/\left(\text{Q}3-\text{Q}1\right)\right]\times \text{P3 +}\left(\text{Tg4u-Ted}\right)$$

Although in the above examples time periods P1 and P2 may be provided to eliminate or reduce the influence of ambient light Ls, for example, in the case of a location where ambient light Ls is not present, such as a darkroom or the like, or when the amount of ambient light Ls with respect to the reflected light Lr is small, and thus the influence of ambient light Ls is small, then the round trip time period .DELTA.P only from the times P3 and P4 be determined. In particular, the round trip period .DELTA.P be calculated using the following equation (F9). $$\mathrm{\Delta }\text{P}=\left(\text{Q}4/\text{Q}3\right)\times \text{P}3$$

[Second Distance Measuring Device 300B]

A distance measuring device (hereinafter referred to as a second distance measuring device 300B referred to) according to a second embodiment will be explained below with reference to the 21 and 27 to be discribed. In 27 designated V1 a tension V1 in the case of the first photoelectric conversion element 10A or a first voltage in the case of the second photoelectric conversion element 10B , and V2 denotes a second voltage in the case of the second photoelectric conversion element 10B ,

As in 21 shown comprises the second distance measuring device 300B approximately the same structure as the above-mentioned first distance measuring device 300A but differs from it in that instead of the third light receiving device 100C a fourth light receiving device 100D is used, which is a fourth light receiving unit 104D has (see 27 ).

<Outline of Fourth Light Receiving Device 100D>

The fourth light receiving device 100D performs an appropriate signal output when a reset fault is to be removed. In particular, with the above-mentioned third light receiving device 100C After the first to fourth capacitors Ca1 to Ca4 all have been reset, become the first to fourth switching elements SW1 to SW4 each turned ON, creating photoelectrons which are in the charge collection unit 26 located, the first to fourth capacitors Ca1 to Ca4 be assigned. Further, in order to increase the signal amount after such operations are performed a plurality of times, the signal amount is voltage-converted and read out by an external circuit. However, when resetting each cycle (between frames) due to a disturbance from the circuit configuration, since the reset voltage is not constant between frames, different levels of reset disturbance components become the first to fourth capacitors Ca1 to Ca4 added.

Thus, with the fourth light receiving device 100D Potentials immediately after a reset of the first to fourth capacitors Ca1 to Ca4 is read out (reset voltage output) and then voltage outputs are read out (signal output) according to the signal changes occurring in the capacitors Ca1 to Ca4 are stored thereafter so that reset perturbation components can be removed by respective difference operations.

<Details of the fourth light receiving device 100D>

As in 27 shown has a fourth light receiving unit 104D from the fourth light receiving device 100D substantially the same structure as that of the above-mentioned third light receiving device 100C but differs from that in that first to fourth charge-holding units Cb1 to cb4 and first to fourth charge transfer units ST1 to ST4 contained therein.

(First to fourth charge holding units Cb1 to Cb4 / First to fourth charge transfer units ST1 to ST4)

The first charge-holding unit Cb1 is formed, for example, by a capacitor of a MOS structure connected to the drain of the first switching element SW1 is connected, and is arranged such that gate drive signals (first collective signal Sa1 (high level) / first output signal Sb1 (low level) the gate thereof from the gate driver circuit 306 be supplied.

The first charge transfer unit ST1 is formed for example by an n-channel MOS transistor, wherein the source with the first charge-holding unit Cb1 connected, the drain to the first capacitor Ca1 is connected and a gate drive signal (first transfer signal St1 ) is supplied to the gate thereof.

Consequently, according to a supply of the first collection signal Sa1 from the gate driver circuit 306 with respect to the gate of the first charge holding unit Cb1 a potential spot below the gate of the first charge-hold unit Cb1 lowered and photoelectrons, which by the first switching element SW1 be transferred, are temporarily collected. Thereafter, in accordance with a supply from the first output signal Sb1 with respect to the gate of the first charge-hold unit Cb1 along with a supply of the first transfer signal St1 (high level) with respect to the gate of the first charge transfer unit ST1 in the first charge-holding unit Cb1 stored photoelectrons to the first capacitor Ca1 transferred. Since the gate of the first charge-holding unit Cb1 and the gate of the first charge transfer unit ST1 can be controlled independently of each other, charges to the first capacitor Ca1 be transferred without causing residual charges in the first charge-holding unit Cb1 left over.

The second to fourth charge-holding units Cb2 to cb4 and the second to fourth charge transfer units ST1 to ST4 are the same as described above, wherein gate drive signals (second to fourth collective signals Sa2 to Sa4 (high level) / second to fourth output signals Sb2 to sb4 (low level)) from the driver circuit 306 each of the gates from the second to fourth charge-holding units Cb2 to cb4 and gate drive signals (second to fourth transfer signals St 2 to St 4 ) from the driver circuit 306 each of the gates from the second to fourth charge transfer units ST2 to ST4 be supplied.

The first to fourth charge-holding units Cb1 to cb4 may also be formed by embedded photodiode structures or by parasitic capacitances.

[Operations of Second Distance Measuring Device 300B]

Operations of the second distance measuring device 300B are substantially the same as those in the above-mentioned first distance measuring device 300A , For example, as in the 24 and 25 shown in the first collection period TCA1 from each cycle Cm first to fourth collective signals Sa1 to Sa4 each of the gates from the first to fourth charge-holding units Cb1 to cb4 fed, whereby photoelectrons, which by the first switching element SW1 in the time period P1 from every second collection period TCA2 in the first charge-holding unit Cb1 are stored, photoelectrons, which by the second switching element SW2 in the time period P2 be transferred in the second charge-holding unit Cb2 are stored, photoelectrons, which by the third switching element SW3 in the time period P3 in the third charge-holding unit cb3 are stored, and photoelectrons, which by the fourth switching element SW4 in the time period P4 in the fourth charge-holding unit cb4 get saved.

In this way, as the initial setting means for the read-out period Tr in each cycle Cm, the first to fourth capacitors become Ca1 to Ca4 reset after signal charges in the first to fourth charge-holding units Cb1 to cb4 were saved. In particular, according to first to fourth reset signals sr1 to sr4 which relates to the first to fourth reset switches SR1 to SR4 (ie, the voltages applied to the respective gates of the first to fourth reset switches SR1 to SR4 are made high, are made high in level), the first to fourth reset switches are simultaneously turned ON, and predetermined reset voltages Vr are set therein. Thereafter, by sequentially turning ON the first to fourth output switches SEL1 to SEL4 the reset voltages from the first to fourth capacitors Ca1 to Ca4 to an external circuit as first to fourth output voltages Vout1 to Vout4 (reset voltage output).

In addition, then, signals immediately after the reset voltage output from the first to fourth capacitors Ca1 to Ca4 read. In particular, first to fourth output signals become Sb1 to sb4 each of the gates from the first to fourth charge-holding units Cb1 to cb4 supplied together with the first to fourth transfer signals St1 to St 4 which assigns each of the gates from the first to fourth charge transfer units St1 to St 4 are supplied, whereby in the first to fourth charge-holding units Cb1 to cb4 stored photoelectrons each to the first to fourth capacitors Ca1 to Ca4 be transferred. In addition, by sequentially turning ON from the first to fourth output switches SEL1 to SEL4 , a voltage corresponding to the photoelectrons (charge amount Q1 ), which in the first capacitor Ca1 are stored, and a voltage which the photoelectrons (charge amount Q2 ), which in the second capacitor Ca2 saved are each through the first output element TR1 and the second output element TR2 amplified, and such voltages are considered the first output voltage Vout1 and the second output voltage vout2 and further, a voltage corresponding to the photoelectrons (charge amount Q3 ), which in the third capacitor Ca3 are stored, and a voltage which the photoelectrons (charge amount Q4 ), which in the fourth capacitor Ca4 are stored, respectively by the third output element TR3 and the fourth output element TR4 amplified and such voltages are called the third output voltage Vout3 and the fourth output voltage Vout4 is output (signal output).

By determining the difference between the reset voltages read out in the reset voltage outputting step and the signal voltages read out in the signal outputting step, signals can be read out without having any influence on the reset voltage values. As a method of determining the difference, a calculation thereof can be realized, for example, by a correlative double-sampling (CDS) circuit.

The photoelectric conversion element, the light receiving device, the light receiving system and the distance measuring device according to the present invention are not limited to the above embodiments, and it is understood that various additional or modified structures could be used therein without departing from the spirit and spirit of the present invention. A few examples are described below.

Modified Example of Photoelectric Conversion Element 10

For example, as in 28 As shown, an embedded MOS diode may be used in which an n-type impurity diffusion region is formed on the surface of a p-type impurity diffusion region.

[Third Photoelectric Converting Element 10C]

A photoelectric conversion element (hereinafter referred to as a third photoelectric conversion element 10C designated) according to a third embodiment, as in 29 and 30 has substantially the same structure as the above-mentioned first photoelectric conversion element, but differs from that in that embedded photodiodes BPD are formed between the first MOS diode and the second MOS diodes.

With the first photoelectric conversion element, a case occurs in which a potential (potential spot higher than potential spots below the second electrodes) acting as a barrier to the photoelectrons is interposed between the first MOS diode and the second MOS electrode. Diodes is present. Thus, with the third photoelectric conversion element, by forming embedded photodiodes between the first MOS diode and the second MOS diodes, as in FIG 31 shown between the first MOS diode 18a and the second MOS diodes 18b a potential spot 32c formed, which is lower than the potential points 32b below the second electrodes 16b and higher than the potential sites 32a below the first electrode 16a ( d .H. between the first MOS diode 18a and the second MOS diodes 18b a potential different from the potentials of each of the MOS diodes is applied). Because of this, for example, currently t2 in 3 the photoelectrons 30 below the second electrodes 16b not obstructed by any potential barrier and thus move rapidly below the first electrode 16a , Further, the embedded photodiodes BPD completely emptied devices so that residual charges can be suppressed and the photoelectrons can be completely transferred therefrom. Further, since there is a p-type high-density region in the surface thereof, the occurrence of dark currents can be favorably suppressed.

[Fourth Photoelectric Converting Element 10D]

Next, as in the 32 and 33 has a photoelectric conversion element (hereinafter referred to as a fourth photoelectric conversion element 10D denotes substantially the same structure as the above-mentioned first photoelectric conversion element 10A but differs in that the second electrodes 16b are not present and in their place embedded photodiodes BPD between sections of the first MOS diode 18a are formed. In other words, viewed from the top, the embedded photodiodes are BPD each in an embedded manner between the multiple branching sections 22 in the first electrode 16a arranged. In addition, the branching sections have 22 from the first electrode 16a in the first MOS diode 18a and the embedded photodiodes BPD each rectangular shapes. Of course, the electrode width may vary from the branching sections 22 from the first electrode 16a also be designed so that they themselves gradually to the one electrode section 20 extended.

Operations of the fourth photoelectric conversion element 10D will now be explained. First, in the exposure initialization phase, when the first voltage is applied V1 on the high level voltage V1H goes, as in 34 shown the potential points 32a below the first electrode 16a to a low level and a potential gradient 34 is formed, in which the potential spot of the embedded photodiodes BPB to a position below the first electrode 16b gets lower. Due to this fact migrate according to the potential gradient 34 the photoelectrons 30 , which at the embedded photodiodes BPD be generated at high speeds below the first electrode 16a and in particular among the plurality of branching sections 22 from that.

After that, in the exposure completion phase, when the first voltage V1 to the low level voltage V1L goes as mentioned above (with reference to 5 ), also potential gradients 34 in the longitudinal direction below the plurality of branch portions 22 from the first electrode 16a trained and with time the potential gradients move 34 parallel to the charge collection unit 26 , causing the photoelectrons 30 be caused to travel at high speeds to the charge collection unit 26 to wander.

In this way, in the fourth photoelectric conversion element 10D by a control / regulation of the first voltage V1 , which are connected to the first electrode 16a is applied, potential gradients 34 formed by a difference in the potential sites, which under the first electrode 16a and in the adjacent embedded photodiodes BPD are formed. Therefore, photoelectrons can 30 , which are obtained by photoelectric conversion, at high rates into the charge collection unit 26 are transferred and effectively collected without the appearance of residual charges remaining below the electrodes. In addition, since the first power supply connections 28a from the first electrode 16a are formed at positions which maximum of the charge collecting unit 26 are separated, can photoelectrons 30 below the first electrode 16a , for example below the plurality of branching sections 22 thereof, to be brought at high speeds to the charge collection unit 26 to wander.

[Fifth Photoelectric Converting Element 10E]

Next, as in the 35 and 36 has a photoelectric conversion element (hereinafter referred to as a fifth photoelectric conversion element 10E denotes substantially the same structure as the above-mentioned first photoelectric conversion element 10A but differs in that the first electrode 16a is not present in it and in its place an embedded photodiode BPD is trained. As seen from the top, the embedded photodiode has BPD a comb-like shape in which a plurality of branch portions 22 from a section 20 are branched out, and second electrodes 16b which second MOS diodes 18b each are in an embedded manner between the plurality of branching portions 22 in the embedded photodiode BPD arranged.

Further, a charge collecting unit 26 to collect photoelectrons, which are from the fifth photoelectric conversion element 10E be generated by the same embedded photodiode BPD in a base section 24 (central part in the longitudinal direction) of the one section 20 in the embedded photodiode BPD educated. The cargo collection unit 26 is designed to stand out from the base section 24 from the one section 20 extend in an opposite direction to the branching portions 22 ,

Operations of the fifth photoelectric conversion element 10E should be with reference to the timing diagram of 37 and the potential diagrams of the 38A and 38B be explained.

First, at a time t11 in 37 (Exposure initialization phase) when the second voltage V2 the high voltage V2H will, as in 38A shown the potential points 32B below the second electrodes 16b low and photoelectrons 30 which are generated by an action of light become under the second electrodes 16b and then accumulate in the embedded photodiode BPD at locations adjacent the second electrodes 16b emotional.

Thereafter, at a time t12 (exposure end phase) when the second voltage V2 the low voltage V2L will, as in 38B shown the potential points 32B below the second electrodes 16b high and a potential gradient is formed, in which the potential spot from below the second electrode 16b to the embedded photodiode BPD gets lower. As a result, the photoelectrons become 30 , which are below the second electrodes 16b accumulated, brought to, by the potential gradient 34 into the embedded photodiode BPD to migrate, and in particular to locations below the plurality of branching sections 22 , and further, the photoelectrons move 30 to the cargo collection unit 26 out. In addition, although the second voltage at time t11 in 37 to the high level V2H is adjusted, and although the high level voltage V2H is preferably set to form a potential which is higher than the potential of the embedded photodiode BPD is at locations adjacent to the second electrodes 16b , the invention is not limited to this feature, and a potential lower than the potential of the embedded photodiode can also be formed BPD is at locations adjacent to the second electrodes 16b , as in 38C shown.

[Sixth photoelectric conversion element 10F]

Next, as in 39 has a photoelectric conversion element according to a sixth embodiment (hereinafter referred to as a sixth photoelectric conversion element 10F denotes substantially the same structure as the above-mentioned fifth photoelectric conversion element 10E but differs from it in the forms of the embedded photodiodes BPD and the second electrodes 16b , seen from the top.

In particular, the branching sections have 22 from the embedded photodiode BPD Shapes that gradually become the one section 20 expand, as seen from the top, whereas all of the second electrodes 16b Shapes have so that the electrode widths of them gradually to the one section 20 narrower or narrower, seen from the top.

In the case that potential spots 32c1 of the embedded photodiode BPD be focused and observed, as in the 40A and 40B is shown at the narrow portions, as a result of that, an influence of the surface potential of the semiconductor base body 12 (Silicon substrate), the potential spot 32c1 of such portions is high, whereas the potential spot 32c2 of the wide portions becomes low. Consequently, as in 41 As shown in FIG. 12, the potential sites 32c2 of the branch portions become 22 from the embedded photodiode BPD lowered while the width of the branching sections 22 becomes wider, which leads to the potential spots 32c to the one section 20 lean downwards. As a result, photoelectrons become 30 at high speeds to the charge collection unit 26 emotional.

[Seventh photoelectric conversion element 10G]

Next, as in 40 has a photoelectric conversion element according to a seventh embodiment (hereinafter referred to as a seventh photoelectric conversion element 10G denotes substantially the same structure as the above-mentioned sixth photoelectric conversion element 10F but differs from that in that the width of one area 20 in the embedded photodiode BPD is formed so as to gradually from both ends to a central base portion 24 widening. In particular, the base section 24 formed such that the width thereof, which to the charge collecting unit 26 leads, is greatest.

In the case that the potential spot 32c in the one area 20 from the embedded photodiode BPD is focused and observed, as in 43 As shown in FIG. 5, the potential sites 32c1 of the narrow portions become high, whereas the potential site 32c2 of the wide portion becomes low. Consequently, the potential spot decreases 32c from the one area 20 in the embedded photodiode BPD gradually, and in particular, it is inclined downwards, from both ends to the base portion 24 , In this way, due to the fact that a downwardly inclined potential gradient from both ends of the one area 20 in the embedded photodiode BPD to the base section 24 ( d .H. the cargo collection unit 26 ) is formed, photoelectrons 30 brought at higher speeds to the charge collection unit 26 to wander.

Claims (24)

A photoelectric conversion element for detecting light and converting the light into photoelectrons, comprising: a first MOS diode (18a) having a first electrode (16a) formed on a semiconductor substrate (12) with an insulator (14) therebetween ; and a plurality of second MOS diodes (18b) each having a second electrode (16b) formed on the semiconductor substrate (12) with the insulator (14) therebetween, the first electrode (16a) being away from the first MOS Diode (18a) has a comb-like shape as seen from an upper side thereof in which a plurality of branch portions (22) are branched from an electrode portion (20), and all of the second electrodes (16b) from the second MOS diodes (16); 18b) from the first electrode (16a) are separated and respectively embedded between the plurality of branch portions (22) from the first electrode (16a), as seen from the top thereof, with a potential below the first electrode (16a) from the first MOS diode (18a), and Potentials among the second electrodes (16b) are respectively and independently controlled by the second MOS diodes (18b) such that at least the photoelectrons generated by photoelectric conversion at the second MOS diodes (18b) become the first Within the first MOS diode (18a), a portion corresponding to a base (24) of the one electrode portion (20) of the first electrode (16a) as a charge collecting unit (FIG. 26) is formed. Photoelectric conversion element according to Claim 1 wherein the plurality of branch portions (22) of the first electrode (16a) in the first MOS diode (18a) and the second electrodes (16b) of the second MOS diodes (18b) are each formed rectangular in shape. Photoelectric conversion element according to Claim 1 or 2 wherein: each of the plurality of branch portions (22) of the first electrode (16a) in the first MOS diode (18a) is shaped to gradually increase in width to the one electrode portion (20), of which Seen from the top; and all of the second electrodes (16b) of the second MOS diodes (18b) are formed so as to become gradually narrower in width toward the one electrode portion (20) as viewed from the upper side. Photoelectric conversion element according to one of Claims 1 to 3 wherein first power supply terminals (28a) of each of the plurality of branch portions (22) of the first electrode (16a) in the first MOS diode (18a) and second power supply terminals (28b) of each of the second electrodes (16b) in the second MOS diodes (18b) are formed at positions which are maximally separated from the charge collecting unit (26) as viewed from the upper side. A light receiving device which obtains luminance information of incident light (La), comprising: a photoelectric conversion element (10) which detects the incident light (La) and converts it into photoelectrons; a charge collecting unit (26) for collecting photoelectrons generated by the photoelectric conversion element (10); a capacitor (Ca) which stores the photoelectrons in a predetermined period of time; a charge delivery unit (108) which releases the photoelectrons; a first MOS type switching element (SW1) disposed between the charge collecting unit (26) and the capacitor (Ca) for causing the photoelectrons accumulated in the charge collecting unit (26) to be fed to the capacitor (Ca ) hike; and a second MOS type switching element (SW2) disposed between the charge collecting unit (26) and the charge output unit (108) for outputting the photoelectrons from the charge collecting unit (26) to the charge output unit (108) to control, wherein the photoelectric conversion element (10) comprises: a first MOS diode (18a) having a first electrode (16a); and a plurality of second MOS diodes (18b) having second electrodes (16b), wherein the first electrode (16a) of the first MOS diode (18a) has a comb-like shape as seen from an upper side thereof in which a plurality Branched branch portions (22) of an electrode portion (20), wherein all of the second electrodes (16b) are separated from the second MOS diodes (18b) from the first electrode (16a) and are each sandwiched between the plurality of branch portions (22) of the first electrode (16a) from the upper side seen from; and the photoelectrons are transferred from the photoelectric conversion element (10) to the capacitor (Ca) by selectively controlling an opening / closing of the first switching element (SW1) and the second switching element (SW2), whereby luminance information of incident light (La ) are obtained based on an amount (charge amount) of the photoelectrons transferred to the capacitor (Ca). Light receiving device after Claim 5 wherein: the charge collecting unit (26) is connected to the photoelectric conversion element (10); and the charge-dispense unit (108) is arranged to face the condenser (Ca) while the charge collecting unit (26) is sandwiched therebetween. Light receiving device after Claim 5 or 6 wherein the capacitor (Ca) comprises an MIM capacitor or a MOS capacitor or an embedded photodiode structure or a parasitic pn junction capacitance. Light receiving device according to one of Claims 5 to 7 , where at least the charge Collecting unit (26), the first switching element (SW1), the second switching element (SW2) and the capacitor (Ca) are formed in a light-shielded region (Z). A light receiving device which obtains luminance information of incident light (La), comprising: a photoelectric conversion element (10) which detects the incident light (La) and converts it into photoelectrons; a charge collecting unit (26) for collecting photoelectrons generated by the photoelectric conversion element (10); a first capacitor (Ca1) and a second capacitor (Ca2) which store the photoelectrons in a predetermined period of time; a charge delivery unit (108) which releases the photoelectrons; a first MOS type switching element (SW1) disposed between the charge collecting unit (26) and the first capacitor (Ca1) for selectively assigning the photoelectrons accumulated in the charge collecting unit (26) to the first capacitor (Ca1) ; and a second MOS type switching element (SW2) disposed between the charge collecting unit (26) and the second capacitor (Ca2) for selectively assigning the photoelectrons accumulated in the charge collecting unit (26) to the second capacitor (Ca2) ; and a third MOS type switching element (SW3) for controlling a discharge of the photoelectrons from the charge collecting unit (26) to the charge output unit (108); wherein the photoelectric conversion element (10) comprises: a first MOS diode (18a) having a first electrode (16a); and a plurality of second MOS diodes (18b) having second electrodes (16b), wherein the first electrode (16a) of the first MOS diode (18a) has a comb-like shape as seen from an upper side thereof in which a plurality of branch portions (22) are branched from an electrode portion (20), all of the second electrodes (16b) of the second MOS diodes (18b) are separated from the first electrode (16a) and are each sandwiched between the plurality of branch portions (22) of the first electrode (16a) from the upper side seen; and the photoelectrons are transferred from the photoelectric conversion element (10) to the first capacitor (Ca1) and the second capacitor (Ca2) by selectively controlling ON / OFF states of the first to third switching elements (SW1 to SW3) Luminance information of incident light (La) is obtained based on an amount (charge amount) of the photoelectrons transferred to the first capacitor (Ca1) and the second capacitor (Ca2). Light receiving device after Claim 9 wherein: the charge collecting unit (26) is connected to the photoelectric conversion element (10); the charge collecting unit (108) is disposed so as to face the photoelectric conversion element (10) while the charge collecting unit (26) is sandwiched therebetween; and the first capacitor (Ca1) and the second capacitor (Ca2) are arranged so as to oppose each other while sandwiching the charge collecting unit (26). Light receiving device after Claim 9 or 10 wherein the first capacitor (Ca1) and the second capacitor (Ca2) comprise an MIM capacitor or a MOS capacitor or an embedded photodiode structure or a parasitic pn junction capacitance. Light receiving device according to one of Claims 9 to 11 wherein at least the charge collecting unit (26), the first to third switching elements (SW1 to SW3), the first capacitor (Ca1) and the second capacitor (Ca2) are formed in a light-shielded region (Z). A light receiving system comprising: light emitting means (202) for emitting pulsed light (Lp) with respect to an object (W); a light receiving device (100B) that receives reflected light (Lr) from the pulsed light (Lp) and performs an output in response to a received light amount; and a controller (204) which controls the light emitting means (202) and the light receiving means (100B), the light receiving means (100B) comprising: a photoelectric conversion element (10) which detects the reflected light (Lr) and converted into photoelectrons; a charge collecting unit (26) for collecting photoelectrons generated by the photoelectric conversion element (10); a pair of capacitors (Ca1, Ca2) which store the photoelectrons in a predetermined period of time; a charge delivery unit (108) which releases the photoelectrons; a pair of MOS-type switching elements (SW1, SW2) interposed between the charge collecting unit (26) and the pair of capacitors (Ca1, Ca2) so as to be in charge with each other; Collecting unit (26) collecting photoelectrons selectively to the pair of capacitors (Ca1, Ca2) in synchronization with a drive of the light-emitting device (202); and a third MOS type switching element (SW3) for controlling a discharge from the photoelectrons from the charge collecting unit (26) to the charge output unit (108) in synchronization with a drive of the light emitting device (202); wherein the photoelectric conversion element (10) comprises: a first MOS diode (18a) having a first electrode (16a); and a plurality of second MOS diodes (18b) having second electrodes (16b), wherein the first electrode (16a) of the first MOS diode (18a) has a comb-like shape as viewed from an upper side thereof in which one A plurality of branch portions (22) are branched from an electrode portion (20), all of the second electrodes (16b) are separated from the second MOS diodes (18b) from the first electrode (16a) and interposed between the plurality of branch portions (22 ) are embedded by the first electrode (16a) as viewed from the top; and the controller (204): turns ON a first switching element (SW1) of the pair of switching elements (SW1, SW2), and the photoelectrons from the photoelectric conversion element (10) to a first capacitor (Ca1) of the pair of Capacitors (Ca1, Ca2) transfers, in a first period (WD1), which is within a period in which the pulsed light (Lp) is not radiated from the light-emitting device (202), a second switching element (SW2) of the A pair of switching elements (SW1, SW2) turns ON and the photoelectrons are transferred from the photoelectric conversion element (10) to a second capacitor (Ca2) of the pair of capacitors (Ca1, Ca2) in a second period (WD2) which is is within a period in which the pulsed light (Lp) is emitted from the light-emitting device (202), the third switching element (SW3) turns ON, and the charge-discharge unit (108) controls, to output the photoelectrons from the photoelectric conversion element (10) within a period (WD3) outside the first period (WD1) and the second period (WD2), and luminance information obtained from the reflected light (Lr) based on an amount (amount of charge) of the photoelectrons transferred to the first capacitor (Ca1) and an amount (charge amount) of the photoelectrons transferred to the second capacitor (Ca2). Light receiving system according to Claim 13 further comprising a power source (208B) and a first MOS-type reset switch (SR1) and a second MOS-type reset switch (SR2) for applying potentials from the first capacitor (Ca1) and the second capacitor (Ca2) to initial potentials put. Light receiving system according to Claim 13 or 14 further comprising a first amplifier (Ap1) and a second amplifier (Ap2) for respectively converting into electrical signals from a level corresponding to potentials based on the amount of photoelectrons present in the first capacitor (Ca1) and the second capacitor ( Ca2) are stored. Light receiving system according to one of Claims 13 to 15 further comprising: a first charge holding unit (Cb1) and a second charge holding unit (Cb2) formed by a MOS capacitor or an embedded photodiode-structured parasitic capacitance to temporarily store the photoelectrons that are emitted from the first Switching element (SW1) and the second switching element (SW2) are transferred; and a first charge transfer unit (ST1) and a second charge transfer unit (ST2) constituted by MOS type switching elements for storing the photoelectrons temporarily in each of the first charge holding unit (Cb1) and the second charge transfer unit (Cb1). Holding unit (Cb2) are stored, to the first capacitor (Ca1) and the second capacitor (Ca2) to transfer. A light receiving system comprising: light emitting means (202) for emitting pulsed light (Lp) with respect to an object (W); a light receiving device (100C) which receives reflected light (Lr) from the pulsed light (Lp) and performs an output in response to a received light amount; and a controller (204) that controls the light emitting device (202) and the light receiving device (100C), the light receiving device (100C) comprising: a photoelectric conversion element (10) that detects the reflected light (Lr) and converted into photoelectrons; a charge collecting unit (26) for collecting photoelectrons generated by the photoelectric conversion element (10); first to fourth capacitors (Ca1 to Ca4) which store the photoelectrons in a predetermined period of time; a charge delivery unit (108) which releases the photoelectrons; first to fourth MOS-type switching elements (SW1 to SW4) disposed between the charge collecting unit (26) and the first to fourth capacitors (Ca1 to Ca4) for supplying the photoelectrons to the first to fourth capacitors (Ca1 to Ca4) in synchronization with a transmission of the pulsed light (Lp); and a fifth MOS-type switching element (SW5) disposed between said charge collecting unit (26) and said charge-discharging unit (108) for supplying a supply of said photoelectrons from said charge collecting unit (26) to said charge collecting unit (26). Control unit, wherein the photoelectric conversion element comprises: a first MOS diode having a first electrode; and a plurality of second MOS diodes (18b) having second electrodes (16b), wherein the first electrode (16a) of the first MOS diode (18a) has a comb-like shape as viewed from an upper side thereof in which one A plurality of branch portions (22) are branched from an electrode portion (20), all of the second electrodes (16b) are separated from the second MOS diodes (18b) from the first electrode (16a) and interposed between the plurality of branch portions (22 ) are embedded by the first electrode (16a) as viewed from the top; and the controller (204) controls: irradiation of the pulsed light (Lp) by the light emitting device (202) and ON / OFF switching of the first to fourth switching elements (SW1 to SW4), the fifth switching element (FIG. SW5) turns ON and outputs the photoelectrons to the charge-dispense unit (108) at a time when all of the first to fourth switching elements (SW1 to SW4) are turned OFF and luminance information from the reflected light (Lr) based on an amount (charge amount) obtained from the photoelectrons, which are transferred to the first to fourth switching elements (SW1 to SW4). Light receiving system according to Claim 17 further comprising a power source (208B) and first to fourth MOS-type first to fourth reset switches (SR1 to SR4) for setting potentials of the first to fourth capacitors (Ca1 to Ca4) to initial potentials. Light receiving system according to Claim 17 or 18 further comprising first to fourth amplifiers (Ap1 to Ap4) for respectively converting into electrical signals of levels corresponding to potentials based on the amount of photoelectrons stored in the first to fourth capacitors (Ca1 to Ca4). Light receiving system according to one of Claims 17 to 19 further comprising: first to fourth charge holding units (Cb1 to Cb4) formed by a MOS capacitor or an embedded photodiode structured parasitic capacitance to temporarily transfer the photoelectrons transferred through the first to fourth switching elements (SW1 to SW4) save; and first to fourth charge transfer units (ST1 to ST4) constituted by MOS type switching elements for storing the photoelectrons respectively temporarily stored in the first to fourth charge holding units (Cb1 to Cb4) to transfer fourth capacitors (Ca1 to Ca4). Light receiving system according to one of Claims 13 to 20 wherein a structural element of the light receiving device (100C) is formed by a structural element of a pixel portion of a line sensor array or a two-dimensional image sensor array in which a plurality of pixels are provided. A distance measuring device comprising: a light emitting device (202) which radiates pulsed light (Lp) with respect to an object (W); a light receiving device (100C) which receives reflected light (Lr) from the pulsed light (Lp) and performs an output in response to a received light amount; a controller (204) that controls the light emitting device (202) and the light receiving device (100C); and an arithmetic processor (206) for calculating a distance to the object (W) by a propagation method using the output from the light receiving device (100C), the light receiving device (100C) comprising: a photoelectric conversion element (10) which reflects the same Detected light (Lr) and converted it into photoelectrons; a charge collecting unit (26) for collecting photoelectrons generated by the photoelectric conversion element (10); first to fourth capacitors (Ca1 to Ca4) which store the photoelectrons in a predetermined period of time; a charge delivery unit (108) which releases the photoelectrons; first to fourth MOS-type switching elements (SW1 to SW4) disposed between the charge collecting unit (26) and the first to fourth capacitors (Ca1 to Ca4) for supplying the photoelectrons to the first to fourth capacitors (Ca1 to Ca4) synchronously associated with a radiation of the pulsed light (Lp); and a fifth MOS type switching element (SW5) connected between the charge collecting unit (26) and the charge delivery unit (108) is arranged to control a supply of the photoelectrons from the charge collection unit (26) to the charge delivery unit (108), the photoelectric conversion element (10) comprising: a first MOS A diode (18a) having a first electrode (16a); and a plurality of second MOS diodes (18b) having second electrodes (16b), wherein the first electrode (16a) of the first MOS diode (18a) has a comb-like shape as viewed from an upper side thereof in which one A plurality of branch portions (22) are branched from an electrode portion (20), all of the second electrodes (16b) are arranged separate from the first electrode (16a) from the second MOS diodes (18b), and between each of the plurality of branch portions (16). 22) are embedded by the first electrode (16a) as seen from the top thereof; and when it is assumed that: a radiation start time from the pulsed light (Lp) is taken as a time Teu, a radiation end time from the pulsed light (Lp) is taken as a time Ted, an incident end time from the reflected Light (Lr) with respect to the photoelectric conversion element (10) is taken as a time Trd, ON times taken from the first to fourth switching elements (SW1 to SW4) as times Tg1u, Tg2u, Tg3u, Tg4u, OFF times of the first to fourth switching elements (SW1 to SW4) are taken as times Tg1d, Tg2d, Tg3d, Tg4d, a period of time from time Tg1u to time Tg1d is taken as P1, a time period from time Tg2u to time Tg2d is taken as P2, is taken as P3, a time period from the time Tg4u to the time Tg4d is taken as P4, a time period from the time Tg4u to the time Trd is taken as Psr, an amount from the photoelectrons , w are stored in the first capacitor (Ca1) within the time period P1 when a charge amount Q1 is taken, an amount of the photoelectrons stored in the second capacitor (Ca1) within the time period P2 is taken as a charge amount Q2, An amount of the photoelectrons stored in the third capacitor (Ca3) within the time period P3 is taken as a charge amount Q3, an amount of the photoelectrons stored in the fourth capacitor (Ca4) within the time period P4 a period of time from a radiation of the pulsed light (Lp) to the reflection of the pulsed light by the object (W) and until the reflected light (Lr) is returned, taken as a round trip period ΔP, and the distance between the light source Q4 Object (W) and the light-emitting device (202) and the light-receiving device (100C) is taken as a distance D, i the controller (204) controls the irradiation of the pulsed light (Lp) from the light-emitting device (202) and ON / OFF switching of the first to fourth switching elements (SW1 to SW4) such that ( 1) P1 = P3, (2) P2 = P4, and (3) Tg1u <Tg1d ≦ Tg2u <Tg2d ≦ Teu <Tg3u <Tg3d ≦ Tg4u ≦ Ted <Tg4d, or, Teu <Tg3u <Tg3d ≦ Tg4u ≦ Ted <Tg4d <Tg1u <Tg1d ≦ Tg2u <Tg2d, and the fifth switching element (SW5) turns ON and outputs the photoelectrons to the charge output unit (108) at a time when all of the first to fourth switching elements (SW1 to SW4) are OFF and the arithmetic processor (206) obtains luminance information of the reflected light (Lr) in the time period P3 based on a difference between the charge amount Q3 stored in the third capacitor (Ca3), which ambient light (Ls) and the reflected light (Lr), and the charge amount Q1, which in the first condensa gate (Ca1) corresponding to the ambient light (Ls) obtains luminance information of the reflected light (Lr) in the time period Psr based on a difference between the charge amount Q4 stored in the fourth capacitor (Ca4) which is the Ambient light (Ls) and the reflected light (Lr), and the charge amount Q2 stored in the second capacitor (Ca2) corresponding to the ambient light (Ls), the ratio determined between the luminance information of the reflected light (Lr) in the time period P3 and the luminance information of the reflected light (Lr) in the time period Psr, and the round trip period ΔP calculated based on the ratio between the time period P3 and the time period Psr, and measures the distance D based on the round trip period ΔP. Distance measuring device according to Claim 22 wherein the round trip period ΔP is calculated based on the following equation (1) when the time Ted and the time Tg4u are the same, $$\mathrm{\Delta }\text{P =}\left\{\left(\text{Q}4-\text{Q}2\right)/\left(\text{Q}3-\text{Q}1\right)\right\}\times \text{P3}$$

and the round trip period ΔP is calculated based on the following equation (2) when the time Ted is later than the time Tg4u, $$\Delta \text{P =}\left[\left(\text{Q}4-\text{Q}2\right)/\left(\text{Q}3-\text{Q}1\right)\right]\times \text{P3}\left(\text{Ted Tg4u}\right)$$

Distance measuring device according to Claim 22 or 23 wherein: the controller (204) emits the pulsed light (Lp) a plurality of times to the light-emitting device (202) in each of respective measurement cycles; and the arithmetic processor (206) calculates the round trip period ΔP using the amounts of charge Q1 to Q4 after the photoelectrons are respectively stored plural times in the first to fourth capacitors (Ca1 to Ca4).

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